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Saturday, January 19, 2019

Which Fertilizer to Apply and Why

Q. Nutrients and fertilizers needed by plants are confusing to me. We have people selling “rock dust” to handle some of these nutrients when they are missing from the soil. How do you know which nutrients are important to plants and how much to apply?

A. There are only 16 or 17 “essential” nutrients absolutely required by plants. Some of them are needed in large amounts and some in very small amounts. These 16 or 17 essential nutrients have been placed into two categories; “major nutrients” (needed by plants in large amounts) and “minor nutrients” (needed by plants in smaller amounts).

Conventional Fertilizers


Fertilizers used by many farmers beginning mostly after World War II, sometimes called chemical fertilizers, contain only three or four of the “major nutrients” needed by plants. The application of chemical fertilizers contributed to the “green revolution” in the late 1950s through the '60s. These nutrients included nitrogen, phosphorus, potassium and sulfur. When used correctly, these fertilizers produced miraculous increases in food production.

Problems arose when farmers began relying only on chemical fertilizers and neglecting the organics in the soil. This heavy reliance only on "chemical fertilizers" resulted in soils that were depleted of nutrients and "worn out".

Soil Testing

Common practices before adding fertilizers included testing the soil for nutrients (soil tests) and testing the plant for nutrients (tissue analysis). These tests determine which fertilizers to apply and how much of each is needed. Soil tests and tissue analysis were common, cost effective practices for large scale producers but costly for the home gardener. The problem was that soil tests, at least for homeowners, were expensive.

Nitrogen

For small-scale producers and home gardeners, scientific knowledge, gardening experience and observation are used to determine which fertilizer to apply and how much. For instance, nitrogen causes growth of leaves and stems and a dark green color. When this type of growth is slow or needed, nitrogen might be added.

When to add nitrogen? Looking at the plant and how well it grows and how dark green was is a good indicator whether nitrogen needs to be added or not. Because nitrogen easily washes through the soil or can escape as a gas into the atmosphere (think ammonia), nitrogen is usually the one ingredient in short supply. Always. So nitrogen can be applied in small amounts, every couple months, on a regular basis through the growing season.

Phosphorus

Phosphorus is responsible for rooting, improved flowering and fruiting and for a good oil content in nuts and grains. When these results are needed, phosphorus might be added. Unlike nitrogen, you can get into trouble by adding phosphorus too often.

When is phosphorus needed? Think of what it promotes; roots, flowers and fruit, and oil. So apply it when new plants go into the ground for their root development. Apply it just before plants develop flowers and fruit. And nuts develop with their high oil content.

When other nutrients are seen to be lacking because of how the plant is growing, these are added to the soil or sprayed on leaves to correct these problems. This is not a cost-effective approach for large-scale farmers however.

Potassium

Potassium is forgotten about a lot by people because it does so much but what it does is not seen easily. Potassium deficiency is difficult to see. We do know that potassium is similar to nitrogen in some ways since it moves through the soil fairly easily and doesn't stick around like phosphorus does. We also know that potassium does not cause the same kinds of problems as phosphorus if it's over applied. We think that potassium is needed in about the same amounts as nitrogen by most plants.Apply potassium whenever you can.

When to add potassium? Not as often as nitrogen and more often than phosphorus.

Using Compost

The nutrient content, or fertilizer content, of compost depends on what was used to make it. But in a general way, most compost is pretty rich in plant nutrients.

Compost usually is fairly high in nitrogen and phosphorus. It could be a little deficient in potassium. But there is a lot of variation in the nutrients it contains in compost.Applying the correct amount of compost and mixing it into a soil can add most of the required nutrients in their proper amounts with the exception possibly of nitrogen. Nitrogen might be added to some plants to increase growth and improve its production.


Rock Dust

Rock dust doesn't have a fertilizer analysis listed on the bag like a bag of fertilizer does. It's seldom listed on a bag of compost either but that's because compost can be extremely variable in its nutrient content. Fertilizer laws are very strict in each state. 1 a bag of fertilizers says it has something in it, it better have it or the states weights and measures police could cause some problems.

Rock dust is supposed to add plant nutrients back to the soil. This is where it can become a little bit like black magic. We know there are 16 or 17 essential nutritional elements for plants but rock dust claims a lot more than that. In some ways, it has been very fashionable to add rock dust to your garden soil and many people smile and give that addition a thumbs up.


Make Yellow Leaves on Bottlebrush Green Again

Q. I love my lemon bottle brush shrubs, but the leaves started yellowing. l recently added five inches of organic top soil. Additionally, l think l should add acid. What kind of supplement should l use for a long-term solution?
This bottlebrush is yellowing because it surrounded by rock mulch and planted in native, desert soil.

A. Leaf yellowing can be caused by many different things. With bottlebrush, it is frequently a shortage of available iron to new growth. More importantly, the soil is collapsing resulting in poor drainage and not enough air reaching the roots.
            I see this often when any bottlebrush is surrounded by rock mulch. Over time, the soil around the roots becomes mineralized. In my opinion, all bottlebrush plants, in general, should not be surrounded with rock covering the soil.
This is an example of an iron fertilizer that dissolves in water that can be sprayed on plants with yellow leaves.
            Once leaf yellowing due to a shortage of available iron, it cannot be reversed quickly by adding soil amendments. The most immediate color leaf reversal would be spraying the leaves multiple times, a few days apart, with an iron solution. But the yellowing will return to new growth as the iron runs out.
            Adding an iron fertilizer to the soil, such as an iron chelate, lasts longer, up to about 1 year. It is added in early spring, about now. But the next year you need to add more iron chelate to the soil, before new growth begins.
This is also an iron fertilizer but the iron is added as the chelate with the acronym or nickname EDDHA. This particular chelate holds on to iron regardless of the alkalinity or pH of the soil. This is not true of other iron chelates.

            But when iron is added to the soil, the leaves which are yellow remain yellow. Green leaf color only occurs in new growth which hides the yellow leaves until they drop off. To turn yellow leaves green again requires a spraying the plant with the iron solution I mentioned earlier.
            For the long-term, you must improve the soil where the plant is growing so that the alkalinity of the soil is reduced, and the roots have better access to air. This can be done by adding compost to a soil that has become mineralized and covering the soil with wood chips rather than rock.

This is a compost made from municipal solid waste. The compost is made from waste products from the city and includes human waste or biosolids that has been composted. All compost from municipal solid waste must meet EPA's health requirements before it can be sold to the public.
            When preparing a spray solution that contains iron, follow the label directions. But I suggest using either distilled or reverse osmosis water rather than tap water. This is because of the alkalinity in our tap water. In distilled or RO (reverse osmosis) water this alkalinity is removed. I am concerned that the alkalinity in tapwater might interfere with the effectiveness of your iron sprays.
            I would also include something to make the spray solution “wetter”. In a pinch you can use a liquid dishwashing detergent but it’s not ideal since it contains so many additives such as hand lotions and perfumes. It’s better to use a liquid detergent which is purer such as Dr. Bonners or a detergent made from Castile soap.
This is a liquid detergent, aka surfactant, that I use and purchase online. Notice that it is unscented and it is also certified as organic through Oregon Tilth.
This is another surfactant that I like which is made out of saponins or agave extract that can assist fertilizers dissolved in water to move inside the leaf through the surface.
            Both the purified water and liquid detergent is important because it helps move the iron contained in the solution through the leaf surface and inside the leaf .
            Spray the leaves long enough so that the spray solution begins running off its surface. Spray both the upper and lower surfaces of leaves so that the sprayer is taken inside the plant more effectively.


Sunday, January 13, 2019

My Classes on Fertilizing Fruit Trees Now Available on Eventbrite

Q. I love my lemon bottle brush shrubs, but the leaves started yellowing. l recently added five inches of organic top soil. Additionally, l think l should add acid. What kind of supplement should l use for a long-term solution?

A. Leaf yellowing can be caused by many different things. With bottlebrush, it is frequently a shortage of available iron to new growth. More importantly, the soil is collapsing resulting in poor drainage and not enough air reaching the roots.
            I see this often when any bottlebrush is surrounded by rock mulch. Over time, the soil around the roots becomes mineralized. In my opinion, all bottlebrush plants, in general, should not be surrounded with rock covering the soil.
            Once leaf yellowing due to a shortage of available iron, it cannot be reversed quickly by adding soil amendments. The most immediate color leaf reversal would be spraying the leaves multiple times, a few days apart, with an iron solution. But the yellowing will return to new growth as the iron runs out.
            Adding an iron fertilizer to the soil, such as an iron chelate, lasts longer, up to about 1 year. It is added in early spring, about now. But the next year you need to add more iron chelate to the soil, before new growth begins.
            But when iron is added to the soil, the leaves which are yellow remain yellow. Green leaf color only occurs in new growth which hides the yellow leaves until they drop off. To turn yellow leaves green again requires a spraying the plant with the iron solution I mentioned earlier.
            For the long-term, you must improve the soil where the plant is growing so that the alkalinity of the soil is reduced, and the roots have better access to air. This can be done by adding compost to a soil that has become mineralized and covering the soil with wood chips rather than rock.
            When preparing a spray solution that contains iron, follow the label directions. But I suggest using either distilled or reverse osmosis water rather than tap water. This is because of the alkalinity in our tap water. In distilled or RO water this alkalinity is removed. I am concerned that the alkalinity in tapwater might interfere with the effectiveness of your iron sprays.
            I would also include something to make the spray solution “wetter”. In a pinch you can use a liquid dishwashing detergent but it’s not ideal since it contains so many additives such as hand lotions and perfumes. It’s better to use a liquid detergent which is purer such as Dr. Bonners or a detergent made from Castile soap.
            Both the purified water and liquid detergent is important because it helps move the iron contained in the solution through the leaf surface and inside the leaf .
            Spray the leaves long enough so that the spray solution begins running off its surface. Spray both the upper and lower surfaces of leaves so that the sprayer is taken inside the plant more effectively.


Fertilizer and Water Improves Nut Yield in Stone Pines

Mineral fertilization and irrigation effects on fruiting and growth in stone pine (Pinus pinea L.) crop
V. Loewe
A. Alvarez
M. Balzarini
C. Delard
R. Navarro-Cerrillo3

Subscribe to ResearchGate and read the entire text here

What is already known on this subject?
This is the first study on fertilization and irrigation in an adult intensive P. pinea plantation, providing a first management proposal for the species.

What are the new findings?
Fertilization enhanced fruit production (›82.3%) and vegetative growth while irrigation enhanced only fruiting. Best fruit production was recorded in fertilized and irrigated plots (›60%).

What is the expected impact on horticulture?
Pine nuts can be produced in orchards applying horticulture techniques as in other fruit crops, improving production quality and quantity, overcoming the traditional view as a non-timber forest product (NTFP).

Summary

Introduction  - Stone pine (Pinus pinea L.) is a species of economic interest for its pine nuts. Despite this market, cones are harvested mostly from natural forests. Advances in semi-intensive or intensive management for cultivating it as a fruit tree have been scarce. Fruit development is characterized by a 3-year cycle since pollination to harvesting, making nutritional and hydric management highly challenging.

Materials and methods – We studied the main and interaction effects of fertilization and irrigation on growth and fruiting by a factorial design laid out in an adult stone pine plantation located in central Chile.

Results and discussion – Mineral fertilization had an effect one year later on height growth (+23.5% increase) and one-year-old conelet production (+82.3% increase). After two consecutive years of mineral fertilization, significant positive impacts on diameter growth, height growth and one-year-old conelet production were observed. Irrigation enhanced fruiting but did not impact growth significantly. The highest conelet number was observed in the fertilized and irrigated experimental plots.

Conclusion 

Both cultural practices, applied either individually or combined, are efficient techniques to enhance fruit production of the stone pine.
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This research accessed from North Carolina State University's AgriFoodGateway

Fruit Tree Pruning Focuses on Structure the First 2 Years

When I teach fruit tree pruning I divide the lessons into 2 major categories; pruning the tree for structure and pruning the tree for production.I usually give myself 3 years to establish the tree canopy. I gradually coach the tree into producing fruit by pruning.Right after planting and during the first year it's all about developing the right structure.

Fruit tree pruning classes and other classes are announced on Eventbrite/Bob Morris/Las Vegas

Three Year Progression on Pruning

Year 1:90% focus on establishing the structure.
Year 2: 50% on correcting tree structure and 50% focus on future production
Year 3: 10% focus on structure and 90% focus on production

You have 2 choices about which type of structure you want to give your fruit tree in commercial orchards; open center or modified central leader.

Open center pruning on pluot

Open Center Fruit Tree Structure

The open center structure is usually applied to peach and nectarine. While modified central leader is applied to many apples and pears. The end result is the same where pruning results in more sunlight entering the canopy of the tree. If sunlight is blocked from entering inside the tree canopy, it can result in fruits produced only on the perimeter of the canopy and not throughout it. This results in a higher percentage of fruit with sunburn and overall lower quality.
Fruit Tree Pruning Focuses on Structure the First 2 Years


Which Fertilizer to Use on My Fruit Trees and Grapes?

Q. I wonder what fertilizer you recommend for my fruit trees? The young trees I recently planted in my small orchard are: plum, peach, apricot, lemon, pomegranate, plus several table grape vines.

A. Lisa. Rather than just tell you what I would use, let me give you a little background on fertilizer selection.

To select the right fertilizer I am supposed to tell you that you should test your soil for nutrients first and then make your selection of fertilizer based upon the test results. That's the right answer but it's not always the most cost effective thing to do if you will have only a few trees. The soil test would cost about $75. You can buy a lot of fertilizer for $75. It makes sense to do this if you are a farmer and spending thousands of dollars on fertilizers and you want to get the most "bang for your buck" but for homeowners it doesn't make a lot of sense.

Mineral or Conventional Fertilizers

A reader applied wood chips around the base of the tree covering the area outlined by the tree canopy. Bender board is used in a circle to keep the wood chips away from the tree trunk while it is small.I suggest the wood chips should be at least 4 inches deep covering the soil around the fruit tree.
Most of our soils will support the use of mineral fertilizers from a bag for many years if we have the soil covered with wood chips that slowly decompose in the irrigated areas. If the fruit trees are surrounded by rock on the surface of the soil than the proper fertilizer selection becomes more critical.

Let's say you have your fruit trees surrounded by woodchips. Fruit trees planted in lawns could be put into this category as well. Just be careful of irrigating the 2 together because they have different water requirements. If the trees are surrounded by rock instead of woodchips, they are growing in the soil that's more similar to hydroponics. Fertilizer selection is more critical when fruit trees are surrounded by rock.

Numbers on the Bag of Fertilizer

Mineral fertilizers have 3 numbers on the bag. If the fruit trees are less than 3 years old, use a fertilizer that has the first and third numbers highest. The middle number, phosphorus, can be lower than the other 2. If the fruit trees are starting to produce fruit, use a fertilizer that has all 3 numbers the same value. Use this fertilizer only once at the beginning of the growing season and apply it about 2 weeks before the flowers appear. In Las Vegas, this would be about the middle of January to 1 February. For grapes, this would be about a month later.

Bag of conventional fertilizer called to Flower Power with 3 numbers denoting nitrogen, phosphorus and potassium

Application of fertilizer is frequent enough unless you have very sandy soils. But if you decide to make a second application, and the trees are surrounded by wood chips that are decomposing, only apply a high nitrogen fertilizer. This would be a fertilizer that has only the first number on the bag and the other 2 are zeros.
Another mineral or conventional fertilizer that contains only nitrogen as a plant nutrient source. This type of fertilizer should be applied less often and in smaller amounts because it doesn't last long in the soil.

Phosphorus

Phosphorus, the middle number on the fertilizer bag, sticks in the soil a lot longer than the other 2. Phosphorus is the only one of the 3 listed on the bag that can create some problems in the future if this mineral is continuously applied, over and over. This is the reason I recommend that people have 2 mineral fertilizers on hand. One fertilizer high in phosphorus, the middle number. And the other one high in nitrogen, the first number. The last number, potassium, should be as high as possible in both fertilizers. Potassium is a little bit more difficult to find in bags of fertilizers.


Compost As a Fertilizer Substitute

When you use a rich compost, it has all of the nutrients present. It is applied in a circle around the tree, about a foot away from the trunk or more, and watered, or lightly dug, into the soil. Rich compost is a very nice fertilizer and gently releases the nutrients to the plants over a long period of time. It is really my favorite to use but a good compost rich in nutrients is hard to find. 
When adding compost as a fertilizer, use a rich compost and keep it away from the trunk of the fruit tree at least 12 inches away.
Viragrow in North Las Vegas is the only place I know in Las Vegas that carries a rich compost like this. It is applied as a substitute to the first of fertilizer application. A second application is never needed and may even extend into the second growing year if enough is applied.

Changing from Lawn to Desert Landscape

Q. After 6 years of trying to have a beautiful lawn in Las Vegas, I finally give up. The water company has offered me $3/foot to convert to water smart landscaping. What should I do? Do I add more rocks and plants? Artificial turf? What trees should I use, if any?

A. If you do nothing else after removing the lawn, plant some trees or large shrubs that shade to the West and South exterior walls and windows of your home. This will help reduce air conditioning costs during the summer. These plants should be deciduous, in other words drop their leaves for the winter.

Shade South and West Walls

            Select trees that grow to about the same height as your home. Avoid trees that grow huge. They use more water and don’t really provide any extra savings in air-conditioning costs. A two-story house can handle bigger trees so in your case these should be deciduous trees so they drop their leaves in the winter and allows sunlight to warm the house. I will get back to you with some recommendations on some plants.
Sometimes just a vine on a trellis is enough to shade a wall or entrance from the hot sun.

Choose Desert Trees

I would steer you towards trees that are adapted to desert environments, in other words, “desert trees”.Regardless of the trees you select, plant them a distance from your home no closer than half of their mature height. Plant them no closer together than this either. Dig the holes for the trees at least 3 times the width of their container and no deeper. Smaller trees establish more quickly and grow more rapidly in the beginning than larger trees. Irrigate the soil around plant roots no closer than 3 foot away from the foundation of the home.
Many desert trees have excellent form and good looks like this Mesquite in this desert landscape.

Fake Grass Has Pluses and Minuses

            Personally, I don’t care for artificial grass unless it’s used for a specific purpose other than just covering the ground. It gets terribly hot during the summer if it’s in the sun and requires upkeep. If you go in that direction, start asking some questions because it is not maintenance-free. I wouldn't use artificial turf unless you have a reason to put it in. Aesthetics, or just looking at it, is not a good reason to install it. It's in the sunlight it gets exceedingly hot during the months of about April through September. It starts cooling down sometime in mid-to-late October for the fall months. If the air temperature is about 105° F, and the sun is shining directly on it, the surface temperature of your artificial grass will be about 165° F. I know because I've measured it.

Some artificial lawns look very realistic but they will be also more expensive.

Suggestions

Start appreciating open spaces. That's what concerns water deserts is open areas. Don't fill the entire landscape area with plants. Learn to appreciate what is called "negative space".

Shade the walls and windows of your home on the south and west sides. With a two-story home this requires trees 25 to 40 feet tall.

Don't plant anything closer to the house than 3 feet from it. Apply the irrigation on the side of the plants away from the house or any cement surface such as patios, driveways, sidewalks, etc.

Think of your landscape plants in multiple layers; the tall ones, the medium-sized once, small ones and groundcovers and vines.

Odd numbers of plants are usually more appealing to the eye than even numbers up to about 7 plants. Above that number, the eye doesn't seem to notice the difference.

Repeat plants through your landscape to provide some continuity and rhythm. There is no need for every plant to be different from each other. Repetition or repeating plants is a good thing and landscape design.

Vine Ripened Tomatoes Not Necessarily Healthier

Dynamic Changes in Health-Promoting Properties and Eating Quality During Off-Vine Ripening of Tomatoes

Authors: 
Mohammed Wasim Siddiqui
Isabel Lara
Riadh Ilahy
Imen Tlili
Asgar Ali
Fozia Homa
Kamlesh Prasad
Vinayak Deshi
Marcello Salvatore Lenucci
Chafik Hdider

Publisher: Comprehensive Reviews in Food Science and Food Safety     

Tomato (Solanum lycopersicon L.) fruit is rich in various nutrients, vitamins and health-promoting molecules. Fresh tomatoes are an important part of the Mediterranean gastronomy, and their consumption is thought to contribute substantially to the reduced incidence of some chronic diseases in the Mediterranean populations in comparison with those of other world areas.

Unfortunately, tomato fruit is highly perishable, resulting in important economic losses and posing a challenge to storage, logistic and supply management. This review summarizes the current knowledge on some important health-promoting and eating quality traits of tomato fruits after harvest and highlights the existence of substantial cultivar-to-cultivar variation in the postharvest evolution of the considered traits according to maturity stage at harvest and in response to postharvest manipulations. It also suggests the need for adapting postharvest procedures to the characteristics of each particular genotype to preserve the optimal quality of the fresh product.

 Author's Conclusions

The authors concluded that some of the health benefits and eating qualities provided by tomatoes increase when ripened off the vine and some decrease. It is not all bad as we are led to believe sometimes. The authors remind us that the health benefits depend upon varieties of tomato that have high health benefits in its genetics. Some tomatoes are healthier for us than others and that is not necessarily dictated by when it’s picked Vine Ripened Tomatoes Not Necessarily Healthierand storage conditions. If you want a good tomato for health benefits, choose a variety that has high health benefits to begin with. During off-vine ripening of tomato, most health attributes increase as well as eating quality. Tomato fruit is subjected to complex changes during ripening and postharvest affecting bioactive molecules and health-promoting properties, physical and eating quality-related attributes. Storage effects on tomato quality will also depend mostly on the applied treatment and temperature. Generally high quality is obtained under low storage temperature and mild storage treatment. All the above -reported changes are aiming to accumulate health-promoting compounds during ripening and to preserve as long as possible the shelf-life of the fruit during postharvest storage of tomato fruits under various conditions.

To read this article in entirety Click Here

Thanks to AgriFoodGateway at North Carolina State University for making these publications available.

Leaves Browning on Palm May Be Lack of Water

Q. I moved here a year ago and have yet to figure out what this tree needs to thrive.  I located and uncovered the drippers to make sure it was getting enough water.  I removed a lantana and a Mexican bird of paradise that I thought might be robbing it of moisture.  I think I may need to rake back the rock and provide mulch around the base.


It puts out new growth, but it soon turns brown and the tree looks pretty sad.  I thought that leaving a few of the dead fronds may provide the new growth with shade.  So far that hasn’t helped.

The tree is in the east side of the house and gets morning sun.  It is shaded by the house to the west and a large palo verde tree on the south side of the house. 

Any help would be a life-saver.  My other palms seem to be thriving, but this little guy is sick.




A. It looks like a windmill palm. What I'm looking at looks exactly like a lack of water. I hope you are not watering every day. You should give plants like this a long burst of water and then hold off before you water again. In the summer this might be 2 or 3 days apart. In the winter this could be a a week to 10 days apart.

 Windmill Palm and Drought

Windmill Palm will have leaf scorch a little bit in our climate but not that much. If that exposure is on the south or west side of the house it's probably a bad location for it because of the heat reflected off of the house and also the rock below the palm. That location can be very hot.

 What Todo

You can get some of that leaf scorch to disappear by adding more drip emitters around the palm and making sure that it gets enough water. I am guessing that your palm should receive about 15 gallons each time it's watered. I would have at least 4 drip emitters under that palm, located about 18 inches from the trunk. The amount of water depends on how many minutes the drip operates. Let's say you have it watering for 60 minutes. Then you would need for drip emitters that are 4 gallons per hour located under the palm tree. If your system is on for 30 minutes then I would have 6 drip emitters under the canopy and these are the 5 gallon per hour.

Another alternative is to not use drip emitters but a coil of drip tubing circling the tree.  .Let's again say you are running it for 60 minutes. This tubing would be connected to your irrigation supply line and be about 15 feet long. The tubing would have emitters embedded in the tubing 1 foot apart and they would be 1 gallon per hour emitters. If you are watering for 30 minutes, then use a coil 30 feet long circling the Palm multiple times. The tubing would be put under the rock. In any regard, the problem appears to be not enough water is being applied.

Saturday, January 12, 2019

Desert Horticulture Podcast: Citrus, Landscape Fabric, Lawn Failure

Join Bob Morris' Podcast on Desert Horticulture

This podcast includes discussions of questions posted previously on this blog.

The topics of this podcast are:
Why did my Meyers lemon not produce fruit this year
Why did my Lisbon lemon stop producing fruit when I planted it from a whiskey barrel?
Should I use landscape fabric when installing desert landscaping?
After 6 years of having a lawn, the homeowner gave up and replaced it with desert landscaping


January Freeze May Eliminate Some Citrus Fruit

           I know I will get questions sent to me why their lemon or grapefruit did not produce any fruit this year. They will say, “The tree grew great, but it didn’t produce any fruit!” We had a pretty good freeze in parts of the Valley recently. If your lemon tree or other citrus had flowers, or very small fruit at that time, then that’s why.

Freeze Tolerance of Flowers vs Tree

            Citrus, the entire tree itself, is tender to freezing temperatures in the first place. It’s considered subtropical. The most tolerance to freezing temperatures starts with kumquat, then Myers lemon, grapefruit, followed by some of the oranges, true lemons and finally limes. Freezing damage results in temperatures ranging from about 22° F to 32° F.
            As soon as growth begins, tolerance to freezing temperatures decreases in entire trees. This holds true of all fruit trees. There is no temperature discrimination when the tree is flowering. All fruit tree flowers and young fruit, whether they are apple or citrus, will die when it freezes. Freezing occurs at 32° F. No exception.
            All flowers are tender to freezing temperatures. All fruit trees flowering during freezing temperatures result in dead flowers and no fruit. The tree survives at 32° F, but the flowers don’t. Young fruit trees are more sensitive to cold temperatures than older ones.

Wind Makes Freezes Worse

            Add a light wind to this formula, flowers and fruit for that year are history. There is a debate whether plants succumb to “wind chill” like humans and animals. Let the debate rage. But I guarantee you, if there is wind associated with any freezing temperature, there is more damage than if there were no wind at all. Protect food production areas of the landscape from wind.
            You are lucky. If you don’t like a cold north wind, you go inside the house and get warm. Plants can’t. They must “suffer” through it. Therefore, let them occupy protected spaces in the landscape and they will be more productive and produce better quality food.

Arizona State University's citrus variety descriptions and harvest times.

            Remember, there are microclimates in a landscape. South and west sides are warmer locations than north and east sides of the home. Protect the tree from wind and you have a nice small, warm microclimate that produces better food.

Windbreak Establishment for Gardens in Pahrump, Nevada

Q. I am a recent transplant to Pahrump, Nevada, from Idaho where I was a master gardener. I have an acre property of bare dirt and want to plant all sorts of edibles from tree fruits to vegetables. But first I want to plant a windbreak around the perimeter of my property. I need some advice on how to start. 

A. As you will find out as you talk to more people in the Pahrump area and those that are gardening you will see the temperature in the winter time is one of your major limiting factors. Trees that do not survive below temperatures of 15 or even 10 degrees Fahrenheit during the winter time are not good choices for you so that might eliminate pomegranates, figs, etc.

The Windbreak

     Let's start with the windbreak. I would caution you about is planting a perimeter around your property for a Windbreak. I think some people are making a mistake when they do that with their property. I understand the reason for defining it with some sort of wall but I think that's the wrong approach if you are thinking about a Windbreak.



Diagram of a living windbreak. Area A is the area of competition and equal to about the same height as the plants in the windbreak. This is competition for sunlight, water, etc. B is the "quiet zone" and maybe 5 times the height of the windbreak or even more. This area is the best area for food crops. The overall effects from a windbreak could be up to 30 times it's height. 

    A key component of a windbreak is how much area it modifies. I would suggest for you that you determine which direction winds are coming from that are your primary problems. Put windbreaks as close to your growing area as possible. The most effective when brakes allow about 20% of the wind to penetrate it through and into the growing area. They don't block wind as much as they slow it so it decreases the damage.

     Buy  an inexpensive recording temperature device such as this Taylor instrument available on Amazon. You can get them for less than $15.

Consider Non-living Windbreaks int the Desert

     I would also suggest that you consider nonliving windbreaks around growing areas, particularly around the vegetable and Herb growing areas. These could be things like chain link fence with PVC slats throat through them if you want to put something up that's relatively expensive. Or it can be as simple as reed fencing.
     The area affected by the windbreak is about equal to 5 - 10 times its height. You can see that if you were to plant around your perimeter for a windbreak it won't be very effective because the distance is too far from the growing areas. Plus, if you were to grow big plants on the perimeter they are just going to use a lot more water than a nonliving or even a living when brake that's closer to the growing area. Plus nonliving windbreaks have a smaller area of competition.
     For sure, growing areas are more productive with better quality produce if they have a windbreak. But that windbreak should be as close to the growing area as possible if it's to be effective. Otherwise you're just growing plants on the perimeter of your property that don't do much good. And you have to water them.
     So I hope you will rethink the windbreak options that you would have on your property before you start investing in some plant materials and irrigation to support it. As far as growing during the growing season which is probably behind Las Vegas about 3 to 4 weeks.

Soil Amendments and Sun Shade Cloth in the Desert

     Some of your big problems in growing will will be the use of soil amendments more than you did an Idaho and learning when to irrigate at the right time.
     Sun protection may be a problem for some vegetables because the sunlight here is more intense than it was in Idaho. So some vegetables will perform better under light shade cloth, about 20 to 30% shade and no more than that.
     I will forward to you some contact information on some good growers in Pahrump and start picking their brain. Start with the Pahrump Farmers Market people and get to know them in particular Cherri and her group who are very active in the gardening community there.
     You can always send me some questions to verify some information or if you don't find the information you need. Pahrump have some pretty good soils compared to Las Vegas but that winter low temperature is a major barrier that you have to consider.

Friday, December 21, 2018

Aphids Overwinter near the Soil on Many Plants

Q. I have a small crape myrtle tree with leaves that were constantly wet this year. The ground and plants underneath were always wet. Now that the leaves are gone. I can see the branches are also wet. Another tree I have is perfectly dry and normal. What’s causing this and how can I correct it?

A. This “wetness” was caused by one of the leaf sucking insects, most likely aphids. If you inspect this “wetness” I think you’ll find it is shiny and sticky as well as wet. It probably attracts flies, bees and other insects.
Common occurrence in late fall and early winter before leaves drop are "wet leaves" due to aphids feeding.

            Aphids suck plant juices from the leaves and then exude a shiny, sugary liquid that drops on the leaves, limbs and plants below it. There are about 4000 different kinds of aphids and about 10% of them cause problems to our plants.
            In the eastern US they have a special aphid, called the crape myrtle aphid, that causes these problems only on crape myrtle. Several aphids specialize only on certain plants. But there are also aphids which are general feeders and infest a variety of different plants as well.
In the spring, aphids feeding on new leaves cause the leaves to distort from their feeding. Leaves that have fully developed won't demonstrate this when aphids feed on them.

            Aphids are a huge problem because they reproduce rapidly in the spring without the help of male aphids. Later in the season, females can be found with wings and fly from plant to plant giving birth to living young wherever there are succulent young leaves nearby. If you don’t get them under control, they can spread.
            To add to this problem, ants pick them up and distribute them as well because they like the sugary liquid they produce from sucking plant sap. Controlling ants in the spring is one way to reduce their spread in the spring.
Good reason to clean up your garden area of weeds is to prevent aphids from staying the winter on these plants. They will huddle on the lowest leaves or stem in loose soil or mulch at the soil surface.

            There are lots of predatory insects and even fungi that attack them during the growing season, but their reproduction and spread is so rapid that these biological controls can’t keep up with their rapidly increasing numbers.
            I guarantee there are winged females and overwintering eggs hidden at the base of woody plants and tucked into nooks and crannies on the trunk and stems.
            What to do? Spray both trees with dormant oil this winter to suffocate both the eggs and the overwintering females. These dormant oils are made from paraffin or mineral oil. Neem oil, although it might be effective, is not a dormant oil.
            Select a warm day, without wind and the sun shining, for spraying. Mix the dormant oil with water at the rate recommended on the label. The oil is emulsified and can be diluted with water for spraying.
            Spray the trees from top to bottom, covering the trunk and all the limbs. They like to overwinter at the base of plants where it’s out of the weather so spray there as well. Remove weeds where they can hide during the winter.

Reasons for Palo Verde Limb Dieback

Q. The palo verde tree in our daughter’s yard looks like it has damage. The top has some dead branches in it. We have had to remove some limbs because of this problem. Can it be saved?

A. There are several different kinds of Palo Verde used primarily in desert landscaping. All have tender new growth that can be severely damaged when exposed to intense sunlight. It is important these trees are pruned throughout their lives so that the tree’s canopy shades the trunk and limbs.
If desert adapted trees have limbs removed that expose the trunk or large limbs to direct sunlight and sunburn, borers can be a problem in these trees such as Palo Verde and acacia

            Pruning them in a fashion that exposes limbs and the trunk to intense sunlight causes damage that causes limb death that becomes visible a few years later. It’s a progression that usually starts with bad pruning practices. This progression begins when too much is removed from these trees. When too much is removed, the limbs and trunk are exposed to high intensity desert sunlight.
Exposing the trunk and lower limbs to direct sunlight and sunburn can create future problems to trees like the Palo Verde.

            Intense, direct sunlight on young limbs first causes a discoloration due to intense sunlight. As this direct sunlight repeats day after day, exposed areas of limbs and trunk facing the sun die. Water can’t through dead areas of the trunk and limbs.
            Unless this sunburn causes severe damage, the top of the tree probably looks fine. The tree can still move water around the damaged area from roots to tree branches. The damage could be as much is 50% of the limb and trunk area and the tree looks fine.
This is not Palo Verde but when the trunk and limbs are exposed to intense sunlight for a long period of time, year after year, the intense sunlight can damage or even kill the living part of the tree under the sunburned area. The beginning of this damage can be very attractive to some wood boring insects which can make the damage worse.

            This damage from sunburn attracts insects such as borers that feed on living parts of the tree close to the damaged area. This feeding by borers causes even more damage that reduces water movement to the limbs. Perhaps the first year or two, trunk and limb damage goes unnoticed because the canopy looks fine.
The first sign of sunburn is a discoloration or off-color to the trunk, limbs or even fruit on fruit trees.

            But at some point, damage becomes severe enough that water movement from roots to the canopy is reduced.  Limbs start dying back because the tree can’t get enough water past the damage. This usually happens during the heat of the summer when demand for water is highest.
            The homeowner now notices the limb death in the canopy. The homeowner removes dead limbs. This exposes the tree to more intense sunlight and further damage. Tree damage is so severe and unsightly the homeowner considers removing it. This is the tree “death spiral”.
            What to do? Damage to the tree may be already extensive. Decide whether you can live with this damage or not. If not, have the tree removed. If you decide to keep the tree, then encourage it to heal as quickly as possible. Contribute to this healing by giving it enough water on a regular basis and apply fertilizer in early spring.

High Nitrogen, Quick Release of Fertilizers Keep Plants Green during Cold Weather

Q. Our lawn was beautiful during the summer but started turning brown when it got cold here in Mesquite. This is a fescue lawn and we were told it would stay green all winter long.

A. There are several different kinds of fescue, but the fescue used for lawns is technically called “turfgrass type tall fescue”. Tall fescue lawns stay green through the winter in our Mojave Desert climate if they receive an application of nitrogen fertilizer in late Fall and night temperatures don’t drop below about 15° F.
This is a conventional high nitrogen fertilizer called ammonium sulfate. It is used to feed plants only nitrogen for promoting growth of stems and leaves.Where the nitrogen comes from but conventional fertilizers may contain other ingredients in very small quantities. Some followers of organic principles might call these other ingredients, "contaminants" in the fertilizer. Any fast release slow nitrogen fertilizer will keep plants green longer into late fall and early winter then not applying any nitrogen.

            If the lawn is without nitrogen, and nighttime temperatures drop below freezing, fescue lawns will go dormant and turn brown. Apply a high nitrogen fertilizer or compost to the lawn late in the fall before freezing temperatures.
A high nitrogen fertilizer but derived from dried blood. It is also high in nitrogen and releases it fairly quickly but not as fast as ammonium sulfate. This blood meal is not certified organic by the USDA but many would consider it as "organic" nitrogen.
            You can use any fertilizer if the first number is the highest number on the bag. Examples can be 21-0-0, ammonium sulfate, applied 2–3 weeks before freezing weather hits. In our Las Vegas climate, applications would be around Thanksgiving, or possibly even later if nighttime temperatures don’t drop below freezing.
            Nitrogen, the first number on the fertilizer bag, is responsible for a plant’s dark green color and encouraging new leaf and stem growth. It can also keep plants from going dormant during the winter.
            There is a nefarious side to late applications of nitrogen. Nitrogen applications made in late Summer or early Fall can compromise our winter-tender plants such as many types of citrus. Applications of high nitrogen fertilizer to these plants late in the growing season can cause them to be more susceptible to freezing temperatures. Never apply high nitrogen fertilizers during Fall to plants that might freeze during winter the winter.

Best Time and How to Prune Ornamental Shrubs

Q. I have some shrubs in my yard that are getting rather scraggly looking.  I was wondering when and how far back I can prune it back in to shape.
Shrubs improperly pruned with a hedge shears. Unfortunately, most people do not recognize bad pruning when they see it and now unfortunately are asking for this kind of pruning.

A. First decide if now is the best time for pruning them or not. You can prune anytime during the winter months. Some plants look better through the winter if they are pruned now. Other plants look fine now but might not look as good if you were to prune them.
As shrubs are pruned more and more into a gumball, in a few years they developed exposed strong stabs at the base.
            Remember, if you prune now you will have to look at them the rest of the winter. If these are flowering shrubs, prune them soon after they finished flowering. If the shrubs do not have ornamental flowers, prune them anytime during the winter.
            The best pruning methods remove the oldest growth from the bottom of the shrub with a lopper or hand shears. Hedge shears for pruning shrubs are, as the name implies, for hedges, not for shrubs.

Properly pruned shrubs require to – 4 cuts at the very bottom to keep it looking good and juvenile.

Organic vs Conventional Strawberries: Nutrition and Pesticide Residues

Organic and conventional strawberries: nutritional quality, antioxidant characteristics and pesticide residues


H.B. Kobi1, M.C. Martins1, P.I. Silva1, J.L. Souza2, J.C.S. Carneiro1, F.F. Heleno3, M.E.L.R. Queiroz3 and N.M.B. Costa1,a
1 Federal University of Espirito Santo, Center for Agrarian Sciences, Alegre, 29500-000 ES, Brazil
2 INCAPER – Centro Serrano, Venda Nova do Imigrante, 29375-000 ES, Brazil
3 Federal University of Viçosa, Department of Chemistry, Viçosa, 36570-000 MG, Brazil

What is already known on this subject?
Organic farming may affect the food composition and produce healthier foods than the conventional system, characterized by intensive use of chemical products.

What are the new findings?
Organic farming produced pesticide-free fruits but did not imply on substantial changes in the nutritional quality or antioxidant properties of strawberries.

What is the expected impact on horticulture?
It is expected to encourage the organic farming system in order to produce healthy and pesticide-free strawberries.

SUMMARY
Introduction – Organic farming system may affect the food composition and produce healthy foods. The aim of this study was to compare the nutritional quality, antioxidant properties and pesticide residues of organic or conventional strawberries.

Materials and methods – In a first experiment, organic and conventional fruits from the cvs. Camarosa and Albion were obtained directly from the farmers. Subsequently, ‘Camarosa’ was produced in organic and conventional systems, under controlled conditions. Pesticide residues were analysed in the second trial and the remaining parameters were evaluated in both experiments.

Results and discussion – In the first experiment, the fruits of organic cv. Albion showed higher moisture (91.8%) and lower total solid (8.2%), and carbohydrate (5.7%) contents. ‘Albion’ fruits also showed higher total solid content than ‘Camarosa’ fruits in conventional farming system. Pesticide residues were not detected. Under controlled conditions, organic ‘Camarosa’ fruits had higher moisture (91.5%) and ash (0.4%) contents, whereas conventional strawberries had higher soluble solids (8.5 °Brix), proteins (0.9%) and anthocyanins (17.7 mg 100 g-1). Residues of azoxystrobin, lambda-cyhalothrin and thiamethoxam were detected at values below the limit of detection (<LOD) in all organic samples, and below the limit of quantification (<LOQ) in conventional strawberries.

Conclusion – Organic and conventional production systems do not promote any expressive difference in the nutritional quality or antioxidant properties of strawberries, although the organic farming produced pesticide-free fruits.

Résumé
Fraises biologiques et conventionnelles: qualité nutritionnelle, propriétés anti-oxydantes et résidus de pesticides.

Introduction – Le système d’agriculture biologique peut affecter la composition des aliments et produire des aliments sains. Le but de cette étude était de comparer la qualité nutritionnelle, les propriétés anti-oxydantes et les résidus de pesticides des fraises produites en système biologique ou conventionnel.

Matériel et méthodes – Dans une première expérience, les fruits biologiques et conventionnels des cvs. Camarosa et Albion ont été obtenus directement auprès des agriculteurs. Par la suite, les fraises ‘Camarosa’ ont été produites en systèmes de culture biologique et conventionnel, en conditions contrôlées. Les résidus de pesticides ont été analysés dans le deuxième essai et tous les autres paramètres ont été évalués dans les deux expériences.

Résultats et discussion – Dans la première expérience, les fruits biologiques du cv. Albion ont présenté des teneurs en eau (91,8%) plus élevées, et des teneurs en matières solides totales (8,2%) et en hydrates de carbone (5,7%) plus faibles. Les fruits d’‘Albion’ avaient également une teneur en solides totaux plus élevée que ceux de ‘Camarosa’ produits en système de culture conventionnel. Aucun résidu de pesticides n’a été détecté. En conditions contrôlées, les fruits biologiques de ‘Camarosa’ avaient des teneurs en eau (91,5%) et en cendres (0,4%) plus élevées, tandis qu’en conventionnel, les fraises contenaient plus de matières solubles (8,5 °Brix), de protéines (0,9%) et d’anthocyanes (17,7 mg 100 g-1). Des résidus d'azoxystrobine, de lambda-cyhalothrine et de thiaméthoxam ont été détectés, à des valeurs inférieures à la limite de détection (<LOD) dans tous les échantillons biologiques et inférieures à la limite de quantification (<LOQ) dans les fraises conventionnelles.

Conclusion – Les systèmes de production biologiques et conventionnels ne favorisent pas l’expression de différences de qualité nutritionnelle ni de propriétés anti-oxydantes des fraises, même si l’agriculture biologique produit des fruits sans pesticides.

This is a peer reviewed publication appearing in the International Journal for Tropical and Subtropical Hortculture

Fruits 73 (1) 39-47 | DOI: 10.17660/th2018/73.1.5
ISSN 0248-1294 print and 1625-967X online | © ISHS 2018 

Why Cleanup Around Fruit Trees and Vegetable Gardens

Survival of pathogenic Colletotrichum isolates on dormant buds, twigs and fallen leaves of apple trees in commercial orchards


N.A. Hamada1,ª and L.L. May De Mio2
1 IFPR, Paraná Federal Institute of Education, Science and Technology, Palmas, Rodovia PRT, 280, Trevo da Codapar, 85555-000 Palmas, PR, Brazil
2.UFPR, Federal University of Parana, Department of Crop Protection, 80035-050, Curitiba, PR, Brazil

Introduction – Glomerella leaf spot on apple (Malus × domestica Borkh.), due to a complex of Colletotrichum species, causes severe leaf spot symptoms leading to early leaf fall, and eventual symptoms on fruit before and after harvest. Under the Brazilian conditions, it is the main apple disease responsible for severe damage in all production areas. This study aimed 1) to verify the survival of Colletotrichum spp. in dormant organs, fallen leaves and soil samples from fungicide-sprayed commercial orchards during winter; 2) to verify the survival of Colletotrichum spp. on asymptomatic leaves during the vegetative period; and 3) to identify the species complex and to confirm the pathogenicity of the isolates obtained from different parts of the plant (on fruit and leaves).

Materials and methods – The study was conducted in a commercial orchard during the winters of 2010 and 2011, assessing the pathogen survival on buds, twigs, asymptomatic leaves, fallen leaves and soil samples. Fungal isolates from different substrates were inoculated on fruit (with and without wound) and on leaves of apple cv. Gala to prove their pathogenicity.

Results and discussion – This is the first investigation on the survival of the Colletotrichum complex in apple under the conditions of Brazilian commercial orchards. All isolates (16) from dormant twigs and fallen leaves were identified as C. acutatum species complex. Five (5) isolates from dormant buds were identified as C. gloeosporioides species complex and three (3) as C. acutatum species complex. According to the data collected, Colletotrichum spp. are able to survive during winter in dormant buds, on dormant twigs and fallen leaves, but are most frequent on fallen leaves. The isolates obtained from buds, twigs and fallen leaves were pathogenic on leaves and fruit of apple. Copper sprays during the dormant stage did not completely eliminate the inoculum. The pathogen was not recovered from soil or from asymptomatic leaves with the methodology used.

Conclusion – Fallen leaves on the ground can be a source of inoculum from one season to the next, so they must be considered in disease management programs to avoid the spread of primary inoculum.

My Comments. This again points to the importance of sanitation in growing areas. Pick up fallen leaves, old fruit, remove remaining fruit from fruit trees, and do not leave old debris from the orchard or garden in the growing area unless it has been properly composted. Most other types of plant materials left as a surface mulch not related to the garden or fruit trees is fine.