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Saturday, July 6, 2019

Removing Palm Seedlings from the Lawn

Q. I have a mature palm tree that dropped seeds onto my lawn. Now I have hundreds of palm shoots growing out of the grass. I’ve tried weed and feed products, but they don’t kill them.  Can you give me any suggestions?
Poem seedling pulled from the soil after germinating

A. Palm seeds can live in dry soil for a long time. When they finally get water, they all germinate at once. Keep your lawn thick and dense by mowing high, watered regularly and fertilize it four times a year. Seeds that fall into it have less chance of getting established.

            Try mowing palm seedlings. If the seeds come from a palm that doesn’t sucker from the base, there is a good chance that mowing will kill the palm seedlings. Many palms have a single, central bud at the top of its trunk and once it’s killed or removed the palm dies.
            I know the task is daunting, but palm seedlings pull from the soil easiest immediately after an irrigation and when they are about 12 inches tall.

try this tool to remove palm seedlings

            As a last resort, try lawn weed killers that contain dicamba (Banvel) or triclopyr (Garlon) as part of the ingredients on the label. Both these weed killers control weeds that become woody. Use the highest rate permissible on the label. Mow the lawn first and then apply the weed killer.

Bottle Trees and Leaf Drop

Q. I'm growing bottle trees together with mock orange and roses and these trees drop their leaves in the middle of summer. What can I do to prevent this?
Leaves on the ground beneath African sumac. One of the problems of African sumac is all the leaf litter it can produce in the middle of summer.Bottle trees can do the same thing.

A. I am starting to think differently about bottle trees. I am beginning to suspect that, like African sumac, some trees drop their leaves when it gets hot and others don't. Both of these trees originate from south of the equator in similar climates, one in South Africa and the other in Australia. Regardless, the best you can do is to prevent the soil from getting too dry and water trees 24 inches deep when you water.
Bottle tree limbs can die back with sunburn. Bottle tree is not a true desert plant but it has thin bark that can't handle a lot of direct intense sunlight.

Both of these trees are not "desert trees" but they are used commonly in desert landscapes. Both of them will handle soils that don't have a lot of organics in them so rock mulch is usually not a problem. This is not going to be true of roses or mock orange.
Japanese mock orange doesn't handle desert soils very well and will yellow if the soil is not improved at the time of planting, the soil is covered in rock for several years or if it's watered too often and the soils begin to drown. They don't come from the deserts of Japan.

Leaf drop or leaf litter is a big problem in African sumac and I get a lot of questions about it. It can also be a problem in bottle tree. But it's best to make sure the soil moisture does not drop too low or both of these trees will drop their leaves.
Roses should never be planted surrounded by rock or this will result in about four or five years. They are not true desert plants, just like Japanese mock orange or bottle tree or African sumac

Both roses and our mock orange (Pittosporum tobira) do not handle desert soils very well but they will tolerate a desert climate, high temperatures, low humidity.When I first moved to the desert in 1984, this plant had me confused with true mock orange which is actually Philadelphus coronarius.

So we should differentiate between the true mock orange and this one which I prefer to call Japanese mock orange. Japanese mock orange comes from the same area of the world that gives us Japanese blueberry.If you have been following me and some of the problems with Japanese blueberry in a desert climate, then you will know you don't want to put these plants with the name "Japanese" in front of it in desert soils in a desert climate or you're looking for trouble.
This is what happens to Wheeler's dwarf Japanese mockorange one you put it in full sun, cover the soil with rock and water it every day or too often.

Like I tell people, there is no such thing as the "deserts of Japan". Okay, Japan has one but there are no plants there! So don't treat it like a true desert plant. Both of them are not.Don't get me started on Carolina cherry laurel and the deserts of North and South Carolina! (Except for Jockeys Ridge!)

The default on your situation are the roses and Japanese mock orange. They like soils that are improved over raw desert soil which the bottled tree will be happy about. So cover the soil beneath these plants with at least 4 inches of wood chip mulch. Beneath the mulch spread a couple of bags of high quality compost like Viragrow's Soil Pro.
There goes soil Pro compost is a compost rich in nutrients. No fertilizer will be necessary for one to two years after applying it.

Use a soil moisture sensor to help you judge when to irrigate again until you get it under your belt, and use a long piece of skinny rebar to make sure you gave these plants enough minutes.

A skinny piece of rebar like this three sixteenths inch diameter is good enough to use for determining the depth of watering. Water small shrubs 12 inches deep. Medium-size trees 18 inches deep. Medium to large sized trees 24 inches deep. Really big trees 36 inches deep
 The roses and Japanese mock orange can handle irrigation 12 inches deep while the bottle tree likes watered down to about 24 inches deep. If these plants are on the same irrigation valve, use drip emitters that are high-volume under the bottle tree and use moderate volume drip emitters with the roses and Japanese mock orange.

Tuesday, July 2, 2019

Rabbit Damage and Fruit Tree Survival

Q. I took a three-week vacation in February and when I returned my 25-year-old fig tree had been eaten all the way around the trunk about 18 inches off the ground. I put Elmer’ s glue and tree wrap on to save and it leafed out and produced great figs. What will happen to this tree? What should I do?

A. If rabbits ate the trunk of this tree in a complete circle around the trunk, it’s a goner. Let it sucker from the bottom and start a new tree from the suckers. The suckers will produce a main crop of figs next year and in two years it will be back in production.

Winter rabbit damage

            Rabbits usually go for smaller diameter wood during the wintertime when there’s nothing else to eat. Where rabbits are problem, remove the limbs from about 2 feet off the ground and protect the trunk with chicken wire. Use a 3-foot-long piece of chicken wire that is 2 feet in width and encircle the trunk with it. This helps keep the rabbits at bay.
Chicken surrounding new fruit trees when rabbits are a problem is good winter protection.
            How soon the tree will die depends on how deeply the rabbit ate. There are two thin cylinders of “wood” just under the bark responsible for taking water up the tree, called the xylem, and the other for moving sugars from leaves to theroots for storage, phloem. If the rabbit ate through both completely, the tree will die next year. If the rabbit ate only the outer cylinder, then it will take about three or four years to die.

            Figs are usually grown on their own roots so suckers growing from the trunk or roots will be true to the type of fig tree. The suckers will produce fruit identical to the fruit you’ve been harvesting for 25 years. Select one to three of the strongest suckers and remove the others. These suckers will form the new tree and they will grow rapidly because of the surviving extensive root system.

Planting Peas with Wildly Different Results

Q. I've planted peas and though some of the plants are close to each other they have wildly different results.  Some of the peas were doing very well while others not as well. Same bag of peas, same plant date, same watering and same mulching.  Why the vastly different results?

A. Classic soil or irrigation problem if they are new seed and all the same but some are doing well and others are not. Try amending the soil so consistently and looking closely at how the water is distributed to the plants. Poor drainage and cold soil is the kiss of death to peas.

The reason for improved varieties of vegetables available from vegetable seed producers is consistent results. Make sure your seed comes from a reliable source and the variety is a reliable variety.
            I'm assuming you know that late spring is not the time of year for peas. They were on their way out a month ago or are really suffering with high temperatures. Peas are winter crops and should be planted in November through early spring, provided the soil is warm enough. Pull them when planting warm season vegetables. Unfortunately, they are usually producing well when replacing them with summer vegetables.

How to Increase Production in Raised Beds

Q. What can I do to increase the vegetable production in my raised beds?

A. Add Compost Annually

Improve the soil with a high-quality compost once a year, plant at the right time of year, plant the correct distances apart, follow rotation principles by planting in different spots each year, and fertilize regularly.

Each early spring or fall, add a 1-inch layer of quality compost to the growing area and mix it into the soil 8 to 10 inches deep. When you’re finished, the soil should be firm, not fluffy, and easy to dig with a garden trowel.

Two Books to Get

             Mel Bartholomew’s book on Square FootGardening is a good start for understanding planting distances to improve production in raised beds and Dr. Wittwer’s publication from Nevada Cooperative Extension is a good primer for growing vegetables in the desert.

Rotate Your Vegetables

            Rotate, or move vegetables to new locations each time you plant. This rotation should last 3 to 5 years before you grow vegetables in the same exact locations. In raised beds, this can be as simple as growing tomatoes and peppers at one end of the bed, the next year the other end and then in the middle.

Use Recommended Varieties

I can’t tell you how many times I’ve talked to people who have grown vegetables from seed they purchased at the local hardware store. Those seed can be hit and miss unless you know what you are buying. If you want good quality vegetables, pay a little extra money and buy better quality seed of varieties that you know will work here.

If You Take, You Gotta Give

            If you take from the garden, you must give back to it. Fertilize the garden lightly every month as you are harvesting. This can be as mineral fertilizer, organic fertilizers or compost.

Bedding Plants Yellowing and Dying

Q. My newly installed Penta bedding plants are dying, and the leaves are turning yellow. They are getting plenty of water. Any ideas what is causing them to die so fast?

A. What are Pentas?

Pentas, sometimes called Star Clusters, are summer annuals grown as bedding plants for their color. The same as any other bedding plants, they don’t like unamended desert soils, bad quality landscape soils or desert landscapes. They abhor rock but grow best in soil amended with good quality compost each time they are planted.

Penta bedding plants are from hot, tropical Africa so they like the heat, must be planted in soils with good drainage and fertilized every six weeks because they love rich soils. They don’t grow well in cool or cold desert soils or planted without a good soil amendment. In fact, they suffer badly when temperatures dip to 40° F in the spring or fall so plant them only when you are confident temperatures are warm and getting hotter.

Always Amend Soil for Bedding Plants

            My guess is the soil used for growing the Pentas was poor quality to begin with or a poor quality soil amendment was added to it. If a poor quality soil or amendment was used, water drainage will cause root rot which will cause yellowing of the plants. If they were planted in February or March, they might have been damaged by cool or cold weather which can also cause yellowing.
Soil Pro is a bagged very rich compost available from viragrow in North Las Vegas. If the soil is amended with this compost no fertilizer will be needed for the planting season.
            Add enough good quality compost or soil amendment so that the soil is dark brown, and you can dig in the soil with a garden trowel easily. While amending soil for planting, throw in some 16 – 20 – 0 or comparable organic fertilizers to get their roots off to a good start and the plants established quickly.

Bedding Plants like Moist Soil

            Irrigate bedding plants like vegetable transplants; daily after they are established and twice a day during the two weeks of establishment. If this is a permanent bed for bedding plants, use half inch drip tubing about 12 inches apart for watering rather than the skinny laser tubing which tends to plug. Water with drip irrigation anytime. When using overhead sprinkler irrigation, water between 3 and 5 AM to minimize disease problems and water loss due to wind.

Rich Compost Doesn't Need Added Fertilizer

            If you use a rich, high quality compost then additional fertilizer won’t be needed for the first couple of months. After that, lightly fertilize bedding plants monthly with a high nitrogen fertilizer such as ammonium sulfate or blood meal. If a good compost is used as a soil amendment, then there are lots of nutrients in the soil already.

Growing Figs from Suckers after a Hard Freeze

Q. We brought this fig from Southern California to Pahrump, Nevada, where it’s colder. I tried to protect it through the winter, but I had to cut it back this spring because it froze to the ground. Four or five suckers are now growing from the base of this tree. Can I still get fruit?

A. Pahrump has a colder climate than Las Vegas so expect figs to freeze to the ground after a cold winter but regrow from the base. 

Grafted Vs on Their Own Roots

Plants that freeze to the ground each winter, whether it’s in Pahrump or Las Vegas, should be grown on their own roots, not grafted onto a special rootstock. If grown on their own roots, then sucker growth will produce fruit the following year.Many times pomegranates are on their own roots. And in Nevada there is not yet a reason to buy grapes that have been grafted. That may change in the future.

Briba Vs Main Crop

Here is a mixture of breed the and main crop figs on the same branch
            Expect fruit from figs each year that they freeze to the ground . That’s because fruit is produced on new growth as well as last year’s growth. Figs that freeze to the ground will not produce an early (Briba) crop but will produce a later crop (main crop) on new growth.

Keep the Suckers

            When the majority of suckers are 18 inches tall, remove weak suckers at the ground and leave 5 to 6 strong suckers growing outward. Fertilize the plant once at the beginning of the season and irrigate so that the soil is wet 18 inches deep. If you want fruit, furnish the plant with at least four drip emitters, 12 – 18 inches from the trunk and cover the soil with woodchips. Fig trees that don’t freeze back and get larger require more emitters than that.

Planting Trees and Shrubs in the Desert

Plant Wet

            Most questions I’m getting now revolve around irrigating landscape trees. I think my message about planting in wet soil, and keeping plant roots wet during planting, has gotten through to most people.
            Whenever planting anything in our amended desert soil, make sure the soil is muddy while planting. The soil should stay wet for the first couple of days while these plants are getting established. If you must, build a doughnut from the extra soil taken from the planting holes to hold the water so it stays close to the plant.

Water the Rootball the First Year

            When landscape trees are first planted, landscape workers typically install several drip emitters close to the trunk. This is good. Get to know the make of these emitters and how much water they deliver in gallons or liters per hour. These drip emitters are oftentimes color-coded to indicate from the manufacturer how much water they deliver.Hand water trees and shrubs with a hose the first couple of weeks after planting.

 Movie Emitters Away the Second Year          

During the second year of growth, move drip emitters to about 12 inches from the trunk, and 12 – 18 inches apart. As trees and large shrubs get bigger, add additional drip emitters so that at least half the area under the plant canopy receives water.

Change Irrigation Time on the Clock after 30 Days

            Landscapers set the irrigation clock to water daily or every other day after planting. That’s good for the first week, but after that give the plants enough water so they can last at least two days without irrigating. This means you might need to increase the number of minutes on the clock for some stations.
            I use a 4-foot-long skinny piece of rebar to determine how many minutes to water. After an irrigation, push the rebar into the soil to judge how deep irrigation water drained. Water young trees and shrubs 18 – 24 inches deep, medium-sized shrubs 12 – 18 inches deep and small shrubs 12 inches deep. If the water did not drain deep enough, add minutes until it does.

When to Stop Harvesting Asparagus

Q. We've had a nice asparagus season and now my wife and I are in our annual discussion about when to stop harvesting the spears.
Asparagus can be harvested by snapping the spears which leaves the broken ends above ground.

A. Asparagus season here usually lasts about 6 to 8 weeks in early spring but if the spears are bigger around than your pinky finger, then go ahead and harvest these larger ones. But not the little ones. Let them grow to their full height to rebuild the harvest for next year.
Asparagus spears begin to fern out if allowed to grow

            When asparagus harvest is over, the spears are allowed to “fern” and grow to their full height, about five and a half feet tall. These mature ferns are green and rebuild the roots or crown for the next spring harvest. These mature ferns are cut and removed when the New Year begins and before the early spring harvest.

Figs Have "Eyes" Important for Excluding Some Insects

Q. I opened my fig fruits and there are ants inside and the fruit is rotting from the inside out.

A. Fig fruits have a small roundish opening on the bottom called the “eye”. Sometimes this eye is open and sometimes it’s closed depending on the variety of the fig. Figs that have “open” eyes allow entry of insects inside the fruit which can cause problems like premature softening, an off taste or souring of the fruit. Fig fruits that have “closed eyes” have fewer problems for home growers than those with “open eyes”.

"Eyes" of the fig. The fig on the left has an open "eye" while the one on the right is closed. The open "eye" can allow insects to crawl inside the fruit, like the dried fruit beetle which can cause "souring" of the fruit.

            Ants have been exploring your fig tree and now have found the “open eye “ of your fruit. As this fruit becomes sweeter, the ants have more reason to visit it. Ants carry plant diseases with them from fruit to fruit. They can transfer bacteria or fungi that cause fruit rotting to the inside of your figs.
            Either exclude or kill the ants by applying an insecticide or physically block them from getting to the fruit. Look at products such as Tanglefoot and eliminate routes the ants might use to reach the fruit. Once they find a way around an obstacle, they all will know how to do it in a short period of time.

Dying Twisted Myrtles

Q. Half of my twisted myrtles on the east side of my house are dead-looking with brown leaves. The same plants on the west side of the house are not showing the same condition. I checked the soil water levels with my water meter and they are plenty wet. Do you know what is wrong?

A. The plant is probably the ‘Boetica’ twisted myrtle. It’s native to the Mediterranean region where soils are a little bit “richer” than our Mojave Desert soils but should do well with occasional irrigation and good soil drainage. Think Rosemary, olive trees, star jasmine, Italian cypress, grapes, Spanish dagger, Bay Laurel and roses. These are not a true “desert plant” but will handle drier locations in the landscape during summer months. In fact, they like heat and sun a lot.
            I’m telling you this because irrigation and soil drainage, rather than exposure to sunlight, is extremely important to these plants. These plants do not like wet soils but prefer soils that drain well and are dry after irrigations. If soils are wet because of irrigation or poor drainage,  Mediterranean plants like this one will die from “root rot”. If using a soil moisture meter, irrigate again after the gauge registers about “five” after dropping from “10” immediately after an irrigation.

Keep Horsetails in Containers and Do This

Q. I have numerous horsetails planted in pots in a dry riverbed to keep them from spreading into my landscape. One of these plants appears to be dying and I’m thinking that others will in the future. Is it because they are becoming root bound in the pots? Can they be contained if I plant them in the ground instead?

A.  Horsetails, or Equisetum as it might be called, can become root bound the same as any plant grown in a container. All plants grown in containers must be replanted every few years when they become large. Plants that grow in clumps, like horsetail, are reduced in size through “plant division”. But I doubt this is the problem.

Loves Wet Soil

            Horsetail, unlike most landscape plants, loves wet soils that drain poorly. They grow best when planted near a pond and keeping the soil wet rather than along a dry riverbed. Their native habitat is in marshes and wetlands that are constantly wet. I think the problem is most likely dry soil so look closely at your irrigation practices. In any case, keeping the soil wet should be your first consideration if they are not growing well.

Double Potting

            Do not plant horsetail directly in the landscape. These plants are notorious, aggressive invaders. They will take over a landscape if it’s wet and controlling their spread is very difficult once they are turned loose.Sometimes this is called pot in pot container growing.
            Growing them in containers placed in the landscape requires double potting them; the container with the plant is placed inside a second container permanently installed in the ground. This second container has a 2 to 3 inch layer of rock at the bottom to prevent the containers from lodging.
            You must, must, must twist the inside container in a circle every two or three months to prevent roots or rhizomes from entering landscape through the outside container. If you don’t, the roots will grow through both containers and the plants will establish themselves in the landscape and spread.
            When dividing a bunching perennial like horsetail, remove it from the container and cut the rhizomes that connect bunches together into a single clump. This results in two or three smaller clumps. Replant one of the smaller bunches in the container with fresh soil and reestablish the irrigation. It will become a bunch again, that needs to be divided, in 3 to 4 years.

How to Get Rid of Unnamed Weed in Lawn

Q. My front and back lawn were taken over by what I call small, nettle-head weeds. Walking on them barefoot remind me of sand spurs that I saw in the South. I have been told it was Bermudagrass weed and chickweed but it doesn’t look like the pictures of chickweed I’ve seen.  Could you please identify them and tell me how to get rid of them?

Pictures of the weed sent to me.

A. I could not recognize the weed from the pictures you sent. Maybe one of the readers will recognize it. It has been cut back severely. This weed appears to have a long taproot like dandelion so it could be one of the local thistles like Bull or Desert thistle. Whatever it is, it has a strong central taproot. This tells me it grows for more than one growing season and is probably a very poor competitor for space in your lawn.

Mechanical Weed Control

            Not the easiest, perhaps, but the best way to rid the lawn of this weed is to cut through the central taproot with a sharp knife, or forked asparagus knife, just below the soil surface. Regrowth of this weed is from the “crown” located at the top of the taproot so cutting the taproot below this prevents it from regrowing and eventually kills it. After an irrigation, perform the coup d’├ętat.

Cultural Weed Control

            Thistles of all sorts are difficult to control with weed killers. But nearly all weeds can be kept out of lawns by increasing the grass density. This is done by mowing high at two and a half to 3 inches, or the top setting of the mower, and fertilizing the lawn regularly. Fertilize lawns at least four times each year with a good quality lawn fertilizer. If the lawn is tall fescue, fertilize on Valentine’s Day, Memorial Day, Labor Day and Thanksgiving. High quality compost can be substituted and gives better results and needs applications less frequently.

Chemical Weed Control

Triclopyrere to guess on the herbicide chemistry that might work on this weed, I would guess something okay to use in lawns but has some woody broadleaf weed control in it. This would be a mixture but I would look for either triclopyr (Garlon) or Dicamba (Banvel) in its list of active ingredients.

Spring Slow Growth of Tomato

Q. I planted Roma, Better Boy and Early Girl tomato varieties this spring. Over 45 days later they've not gotten much bigger than when I brought them home from the nursery. 

A. Be careful when mixing woodchips or other woody soil amendments in the soil. These woodchips require a lot of extra nitrogen as they decompose, a.k.a., rot. They will slow growth and cause yellowing if mixed in the soil without any follow-up nitrogen fertilizer applications. It is very important to add extra nitrogen fertilizer to the soil if you decide to mix anything in the soil made from wood products.
            The weather has been colder and wetter than normal. This has also slowed down the growth of warm season vegetables like tomatoes, peppers, eggplant and the like. Be patient.

Wall o water has been around for a long time and it works a little better than hot caps but more expensive. Be sure to warm the soil before putting transplants out in wall of water or cold soils will slow them down.

            Hot caps aren’t used much anymore but those along with Wall-o-water plant sleeves were made to speed up the growth of plants during cool weather. Rediscover these nifty little garden additions. They keep plants warmer and speed the growth of warm season vegetables when weather is cool.
            On the remote chance something else might be going on, inspect some roots of these plants and see if there are any small “balls” growing on them. 

Root knot nematode on tomato

If found this might indicate nematodes are in the soil and a problem. Nematodes infesting plant roots can slow them down as well. Not much you can do if they are present except replace the soil and plants. This is one reason container gardening can be worthwhile. The containers can be sanitized and the soil replaced more easily than in a garden bed.

Reattaching Vines to Painted House

Q. Last week I pulled the vines growing up the sides of my house in order to paint the exterior. These vines included hacienda creeper, Mexican creeper, Senecio, and creeping fig. Is there anything I might do to encourage them to reattach themselves up the wall or must I cut them back to the ground and wait for them to start over? 

If you're looking for some vines for our hot desert climate, take a look at this pamphlet from the University of Arizona for suggestions. Pay attention to the exposure they recommend, north south east or west, shade or no shade, and the temperature they can tolerate. You are playing with fire if you select anything over 25°F for its cold, winter temperature tolerance.

A. Cut them back and they will grow back quickly to their original size. This is because they are already established. Hacienda Creeper and climbing fig should climb up the painted wall again and reattach to the house on their own. These plants have established roots so they should grow up the sides of the house quickly. Creeping fig is perhaps the slowest grower of the group, but it will reestablish itself over time.
            Pull some of the stems toward the wall as they reemerge and they should start climbing. Cut off stems that don’t reattach and those that do will climb faster. Senecio and Mexican creeper are twining vines so they will need some help climbing again. Adequate water, small amounts of compost once a year and regular fertilizer applications will push them to climb faster.

Neglected Peach Tree on Purchased Property – What to Do?

Q. We bought a property in Redding, California, and it has a pretty sad looking peach tree on the property. Many of the limbs are dead and the live ones are dripping sap. Do we need to get rid of this tree? Is there any way to prevent this from happening again?
Not the peach tree in the question but this peach had borers in the trunk and tried to heal the damage. Note the "rolling" of growth over the damaged area.

A. Peach trees are magnets for wood boring insects, a.k.a. borers, in our climate. This is the main reason most peach trees are not as long-lived as other fruit trees. This insect never enters the soil, so the soil is usually not a problem. Only the tree. If the damage to the tree is severe, remove and replace it.
This is borer damage on a young Bramley Apple tree. Frequently the first 2 to 3 years are critical times for tree establishment and prevention of borers. Damage like this is usually on the West or South sides of the tree because of intense sunlight from those directions. Painting the tree trunk with dilute white latex paint is one option for decreasing borer problems during the first few years. It keeps the trunk a little bit cooler.

The Death Spiral

            Once trees are attacked by these types of borers, the tree frequently enter a death spiral and there is not much you can do without using insecticides. Even applying an insecticide is not a guarantee the tree will be cured. Applying a systemic insecticide containing Imidacloprid as a soil drench soon after flowering may kill borers still inside the tree and give the tree some protection for a few months.
Another indicator of borers in fruit trees is the death of a limb or limbs beginning in about July. Death of a limb due to borers opens the tree for more sun damage followed by borers and can lead to the death spiral I mentioned earlier.

Limbs Die during Summer Months

            Limbs dying because of this insect are normally seen during the summer but the damage they cause inside the tree starts in the spring. These insects are attracted to trees damaged by intense sunlight, but sometimes they infest trees that appear not to be damaged at all. As added protection, make sure the tree is pruned, watered and fertilized so that it has a full canopy which protects its limbs and trunk from intense sunlight. It also helps to shade the trunk or paint it with diluted white latex paint.
Sometimes this damage can be scraped or cut away with a sharp, sanitized knife and the area allowed to heal. It's worth a shot.


            Make sure the tree is getting enough water by irrigating it with at least four drip emitters spaced under the canopy. With newly planted trees, these emitters should be about 12 inches from the trunk in a square pattern and more emitters added as the tree gets larger.

Vegetable Seed Germination Temperatures

Vegetables – for Every Season There Are Vegetables

Q. I planted two rows of corn, separated by some peas, but one row closest to the fence never came up. I replanted that row and now one row of corn is really struggling while the other, closest to the peas, is doing well.

Corn is pollinated by the wind, not insects. A lot of corn plants close together will increase the amount of pollen in the area and improve the chances of having ears that are full rather than spotty.

A. Amend the garden soil with compost to improve drainage. Poor drainage can cause a lack of germination. Lightly dust the seed with Captan fungicide to improve seed germination when planted in cold or wet soils. Tear a corner of the seed packet and place a small amount of fungicide inside and shake it. Always wear gloves when planting seed treated with a fungicide.
My staff in Afghanistan treating wheat seed for better germination. Protect your hands and your mouth when handling fungicides used for seed treatment.

            I strongly encourage you to not plant the same type of crops in the same area as previous years. Instead, plant in new locations in the garden bed and rotate them back to this spot only after 3 to 5 years. This technique helps keep plant diseases minimized.
Planting sweetcorn in raised beds requires the right time of year, a good plant density for pollination. Here sweetcorn is planted 12 inches apart in blocks.

            Mixing woodchips into the soil before planting can also cause poor seed germination. Corn needs lots of nitrogen fertilizer when it’s growing. The rotting of woodchips in the soil also requires a lot of nitrogen fertilizer so make sure enough nitrogen fertilizer has been added to the soil to fuel both growing corn and rotting wood chips.
Corn is more closely allied to grasses than other vegetables. Like grasses, corn is a heavy feeder of nitrogen fertilizer. A slight change in the color green in the leaves will tell you if nitrogen fertilizer should be applied. Let the plant tell you.

            Peas are a winter crop while corn is a summer crop and they should not be planted at the same time in the spring unless you are prepared for a short harvest of peas. Also, sweet corn needs more than two rows planted for for its kernels to fill out the ears properly because it is wind pollinated. Plant at least four rows of corn rather than only two. Plant corn in small blocks rather than rows if the area your planting is small so the ears fill out better.
Cornsilk receives the pollen shed by the top of the plant. If temperatures are too high, poor pollination results. This is seen by missing kernels in the ears. Each kernel is connected to a silk. Every silk must receive pollen for a full ear of corn.

            Both corn and peas have large seeds so try presoaking large seeds, sometimes called pre-germinating, before planting to get faster germination. They should soak long enough for the seeds to swell with water. Soak large seed in tepid water for several hours before planting. This allows the seed to start the germination process without planting. But it’s important to plant them at the right time of year; peas in the fall through winter months for a winter crop and corn in mid spring or late summer for an early summer or fall crop.
This is where the pollen comes from at the top of the plant called a tassel.

            When pre-germinating seed, mix a small amount of your favorite water-soluble fertilizer into the fresh water, along with a tiny amount of liquid soap. This speeds up germination. When seed absorbs water at the very beginning, called imbibition, the fertilizer will be taken inside the seed with the water and early growth is more rapid.
This is what everybody hopes for, a full ear of corn. This is a variety called Silver Queen. It's a lot of work to get here.

Woodchip Epidemic

But Woodchips Are Good!

I think there is an epidemic going on of people adding woodchips to the soil as a amendment. Woodchips applied to the soil surface as a mulch is okay but mixing these into the soil can lead to problems if you aren’t careful. 

Part of this trend is fueled by social media like YouTube and Internet discussion groups and experimentation by gardeners with concepts such as Hugelkulture. It works but it must be done correctly.

Tomato failure. Why? Woodchips.I would not add woodchips to an area that has to be dug up every year.

Everything in Moderation

Adding wood debris to the soil for its improvement requires a balance between the carbon load added to the soil in the form of woodchips, water and nitrogen added to the soil at the same time to help it rot. 

Add Nitrogen

These sources of nitrogen help woodchips to decompose and rot without affecting other plants growing in the same area. Without this additional nitrogen, plants growing in the area yellow and may die. Seeds planted in these types of amended soils fail to germinate.
            Additional nitrogen can be added by chopping up kitchen scraps, green waste from the yard such as leaves and grass clippings and even mixing in commercial fertilizers high in nitrogen such as 21-0-0. Rotting is sped up by turning it and keeping it moist.

More Leaf Drop in Apricot - Its Hot, Check Irrigation!

Q.  We have an apricot tree about 5 years old.  It’s always seemed happy but this year it leafed out beautifully then last week started losing it’s healthy green leaves on one side.  Apricots are on the tree, but not developed yet. Now half the branches on that one side are leafless.

A. I looked at the picture and it looks like a watering problem; not enough water getting to the upper limbs and causing drought and leaf drop. Drought occurs first on the hottest side, the sides facing the sun. If you remember, we had a hot spell just before the weather cooled off again.

See if the tree is still alive

            Go to your tree and bend the smallest branches to see if they are still supple. For most fruit trees, if this problem is temporary they will be supple and bend easily without breaking. If this is the case, expect the tree to produce more leaves and branches after a couple of weeks if it is given water.
            Following the KISS rationale, we can eliminate the less likely disease problems, a weed killer spray drifting toward the tree, fertilizer misapplications and the like.
            Now, the cause of the drought. Water shortage to these limbs could result from not enough water applied to the tree or in the right areas, or damage to the trunk or limbs by boring insects tunneling through the trunk and limbs and interrupting the flow of water. If sap is not seen on the trunk or branches or the bark is not peeling off, then we can also probably eliminate borers.

Q. When is the best time 
to check fruit trees for borers?
A. The day after it rains.

            Leaf browning and dropping from borer damage usually happens around June or July when it gets hot. But inspect the trunk and limbs anyway for signs of borers.

Water, Water Everywhere

            That leaves us with irrigation, which is the most likely reason particularly because of the unusual weather. A five-year old tree should be pretty big so its water needs are also large unless you have purposely kept it smaller through pruning. A five-year old tree probably needs around 25 to 30 gallons of water each time it is irrigated. This water should be applied to as much area under the canopy as possible.

How Many Emitters?

            The minimum number of emitters needed for a five-year old tree is four; each located about 12 to 18 inches from the trunk in a square pattern surrounding it. Six emitters arranged in a circle 18 inches from the trunk would be even better. Apply the water long enough so it penetrates to about 18 inches deep. I don’t know how many minutes this would be because each irrigation system is different. But keep the number of minutes the same as before and increase the size of the drip emitters instead if the water is not deep enough.

Giving the Tree the Shaft

            To judge if you applied enough water, use a long steel rod, like a three-foot length of rebar, and push it into the wet soil after an irrigation. Do this in about three or four locations to get an average irrigation depth.
            This time of year, water about Three times a week if the soil is covered in woodchips. A thick layer of mulch on top of the wet soil usually saves one or possibly two days between irrigations. In June, water three times a week when it starts to get hot. If you aren’t sure when to irrigate, use a soil moisture meter like those for houseplants, to measure if the soil is dry enough to water again. Don’t trust the surface of the soil to tell you. Push the tip in the soil about 4 to 6 inches deep to get a measurement.

Black Spots on Tomato and Lettuce

Q. I have six tomato plants grown from seed, all indeterminate. They were growing in two-year-old, rich soil mix containing compost that produced a lot of tomatoes last year. The leaves of the tomato plants developed okay but then they got spotty and dried up. No blossoms at all. The leafy vegetables grew well but the older leaves at the bottom of lettuce also developed black spots, became yellow and died.

This gardener has been growing tomatoes this gardener has been growing tomatoes for over 30 years in the Las Vegas Valley. He seems to favor Celebrity but he grows them in the same spot year after year. We've got to learn to rotate vegetables so they are not grown in the same spot year after year.

A. I looked at the pictures you sent. Tomato diseases are tough to diagnose with pictures but I think this might be bacterial leaf spot. I first got suspicious when you said you started these plants from seed. Then I considered the wet, cool weather, which is perfect for this disease to develop, and concluded it was probably bacterial leaf spot. 

Google some pictures of this disease on tomato and lettuce and see if you think it looks like the same and let me know. Leaf spot diseases such as bacterial leaf spot can occur on lettuce as well.

            Leaf spot diseases can infect the plant from seed contaminated with this disease agent. Most seed will have this disease present so applying a hot water or chlorine seed disinfection helps reduce this disease possibility. Methods for doing this at home can be found on the Internet or I can forward instructions to you.
            Cool and wet weather, perfect weather for this disease, promotes bacterial leaf spot if it’s present. This disease can become a problem if the growing area has not been cleaned up and old fruit and fines are present. 

Also, don’t grow vegetables in the same location year after year (implement crop rotation) to reduce the possibility of this disease, and several others, from occurring. Crop rotation can be as simple as not growing the same vegetable in the same location in a raised bed year after year.
            Indeterminate tomatoes have vines that keep getting longer and longer while determinate tomatoes produce short vines and flower sooner. For earlier production of tomatoes, choose determinate tomatoes rather than indeterminate ones. 

Determinate tomatoes are better for most home gardens in the hot desert anyway because you want to produce tomatoes as quickly as possible. Hot weather can come quickly and air temperatures above 95F can stop tomatoes from forming from the flowers.
            If you select indeterminate tomatoes, and then fertilize them with high nitrogen fertilizers, the plants will grow beautifully but produce few flowers until they get older. When growing indeterminate tomatoes, don’t fertilize plants after planting until they begin to bear fruit.

Monday, July 1, 2019

Rotating Vegetable Crops to Prevent Diseases

By Robert Morris
Prepared for ACDI/VOCA on March 10, 2009

Rotating fields to different crops each year is one of the most important and easily implemented disease control strategies for farmers. This practice avoids the buildup of many plant diseases in the soil. The longer the rotation before coming back to the crop, the less likely a disease will occur. 

Because diseases usually attack members of the same plant family, it is best to avoid planting crops after each other that belong to the same family. Insect damage may increase when the same crop is planted in the same area over several years as well. Here are some common vegetables and the families they belong to.

  • Tomato Family: Tomato, potato, eggplant, peppers
  • Cucumber Family: Cucumber, melons, squash, pumpkin, gourd
  • Lettuce Family: Lettuce, endive, salsify, Jerusalem artichoke
  • Onion Family: Onion, garlic, leek, shallot, chive
  • Carrot Family: Carrot, parsnip, parsley, celery
  • Cabbage Family: Cabbage, broccoli, cauliflower, Brussels sprouts, kohlrabi, turnip, radish, Chinese cabbage, kale, collards, rhutabaga
  • Beet Family: Beet, Swiss chard, spinach
  • Pea Family: Peas, snap bean, lima bean, soybean
  • Okra Family: Okra
  • Corn Family: Sweet corn, field corn, wheat, barley, oats

Some choices of crop rotations include Pea Family to Corn Family, Lettuce Family to Cucumber Family, Cucumber Family to Cabbage Family, and Cucumber Family to Corn Family. Rotating beans with a grain crop such as barley, oats, rye, wheat, or field corn or with a forage crop is very beneficial for root-rot control. One or two years in a grain crop is often long enough to prevent severe root rot when the field is not heavily infested with this disease.

Some diseases that come from the soil are not easily controlled by rotation. Such diseases can live a long time in the soil and are not affected by rotation. Examples include clubroot that attacks the Cucumber Family, Phytophthora blight, and Fusarium wilt of several crops. Other diseases attack so many vegetables that they can survive indefinitely on many different plants including weeds. These diseases include Sclerotinia, Rhizoctonia, Verticillium and root-knot nematodes. 

Many diseases can survive successfully because they can live on plants and plant parts left in the field after harvest. However they are unable to survive once the plants left in the field decompose. Destruction of plants and parts of plants left in the field after harvest can eliminate this problem. Plowing the field after harvest and before letting the soil rest can reduce the amount of disease that will survive.