Not Too Late to Apply Dormant Oil

Not Too Late to Apply Oil: It used to be called dormant oil. Everyone thought the only time you could apply it was the winter. Now it's called horticultural oil b...

Protect Nectarine Fruit from Scarring

Protect Nectarine Fruit from Scarring: Do you want fruit from your nectarine tree that looks like this? Western flower thrips and damage to nectarine I didn't think so....

Viragrow Delivers!

Loss of Bark on Ornamental Plum Due To Borers

Q. I have a flowering plum which I first noticed this morning has a problem with loss of bark on the west side of the trunk. My yard faces south. What should I do?

Borer damage to ornamental plum on the west side of the trunk

A. This is borer damage to the trunk. You can read more about this insect and the type of damage it does to ornamental and fruit trees and how to correct it from the links below.

Your picture was extremely helpful but the other thing that keyed be in was that you said it was on the west side of the trunk. This is the side of the trunk getting very hot in the late afternoon. Heating up on this side from the sun leads to sun damage. Sun damage to the trunk attracts boring insects. They like to lay their eggs on these kinds of damaged sites.

Concentrated form for commercial applicators and professionals

Since you are not eating the fruit of this tree you can apply a liquid soil drench insecticide. This product comes in several trade names so I cannot list them all but the key chemical ingredient is Imidacloprid. This will be listed in the active ingredients.

Homeowner version found in many nurseries and garden centers

Follow the label directions and apply it after it finishes blooming.  Otherwise take a clean knife and clean up the damaged area and let it heal as explained in the posts on my blog below.

http://xtremehorticulture.blogspot.com/2015/08/identifying-their-damage-and.html

http://xtremehorticulture.blogspot.com/2014/02/mechanical-control-of-borers-in-fruit.html

Stopping or Suppressing Flowering and Fruiting of Ornamentals

Q. Is there anything to stop or suppress flowering of a Palo Verde tree? My wife is allergic to the pollen and unless I can mitigate its effects, I guess it's gone. 

A. You are hitting on a very important topic as we convert our landscapes into water conserving desert landscapes. Before the conversion of landscapes from traditional to desert landscapes, the three biggest problem trees for allergy sufferers were mulberry, pine and olive.

Olive flowers just before they begin to open

Female mulberries produce only fruit. Male mulberries produce only pollen. Years ago fruitless (male) mulberry was planted because it was a great shade tree for the desert, water for landscapes was abundant and the male tree produced only pollen. Female mulberry trees made a mess on cars and sidewalks and birds who ate the fruit dropped it everywhere.

Pine getting ready to release pollen from the male flowers

Pine trees and olives were different. They also produced allergenic pollen but pollen and fruit were produced on the same tree; male and female trees were not separate from each other. Fruitless (and flowerless) olive was discovered, promoted and adopted as the only olive tree which could be planted in major urban centers like Las Vegas because it produced no flowers and hence no pollen.

Mulberry flowers getting ready to release pollen

Palo Verde produces allergenic pollen on flowers that are both male and female in the same flower. Comparing them to the above 3 trees, they are more similar to olive than pine or mulberry. There are no flowerless Palo Verde, unlike the olive.

Olive fruit can sometimes be prevented by spraying the tree with a product like Florel Fruit Eliminator. (contains ethephon). This product also controls the fruiting of several ornamental plants (and sometimes the flowers) when applied just before bloom. Depending on your Palo Verde, flowering will probably be in April or May in our Las Vegas climate. You can read the label below

View the Florel label

I hesitate to recommend this product because if it is applied at the wrong dose it can cause leaf drop or possibly damage the tree. There is a recommended rate for several ornamental trees including olive but Palo Verde is not listed on the label. Use it at your own risk but if you are thinking about removing the tree anyway it might be worth a shot. I am not sure who sells it in Las Vegas but you cannot purchase it online.

Thin Peaches and Nectarines

Peach fruit too close together

Thinning, or the removal of fruit by hand, is an important step in growing larger and higher-quality peaches and nectarines. Enough fruit is removed from the tree so that the remaining fruit gets larger. We typically target this fruit to reach the size of 3 to 4 inches in diameter.

Peach fruit before thinning

Peach fruit after thinning

I like to relate this concept to something we can all appreciate; money. If you have an income that does not get any bigger and you have a family, the larger the income the more money you can spend on each individual in the family. If you have a dozen children then each of the children will receive less. If you have 3 children, then you can afford to spend more on each of those 3 children.

Peach fruit before thinning

Is the same with the fruit tree. The income for the tree is the sunlight, water and nutrients taken from the soil. A tree that is 10 feet tall can only gather a certain amount of light, water and nutrients from the soil. If the tree has 1000 fruit on it, the fruit may be the size of a coin. But if the fruit is thinned so that only 200 fruit remain, then the fruit might be the size of a small ball. Thinning of fruit is important to increase the size of the remaining fruit.

Peach fruit after thinning

Remove enough peach and apricot fruit so that the remaining fruit is 4 inches apart. As you are thinning or removing the fruit, remove fruit that is damaged or deformed 1st. Favor fruit that hangs from the bottom of the branch rather than the top of the branch. It is harder for birds to pack fruit on the bottom of the branch than the top of the branch.

Problems When Planting Tomatoes, Peppers and Eggplant

Two  Major Problems When Planting in Desert Garden Soils

The first problem regards the organic content of the soil. When growing many vegetables, they perform better with improved soil aeration around the roots. This is not necessarily true of root crops such as carrots or onions but is more important for tomatoes, eggplant, peppers and the like.

To improve soil aeration add a 1 inch layer of compost and dig or till it in each growing season. If you use compost make sure you pay attention to the carbon to nitrogen ratio (C:N) of that compost. The lower the carbon to nitrogen ratio, the more nitrogen is added to that garden soil. If the carbon to nitrogen ratio is 20:1 or lower, you may not need to add any nitrogen fertilizer for 1 to 2 months after transplanting. Adding a rich compost with a low carbon to nitrogen ratio and then adding a high nitrogen fertilizer at the same time may result in very bushy plants with no flowers until the nitrogen begins to run out.

The second problem involves water. Garden soils and soils in raised beds have additional compost added to them prior to planting. Frequently compost and soil mixes blended in desert environments are high in salts. These are not the bad salts but they are good salts in high enough concentration where they might damage plants if soils remain dry at the time of planting. This is usually not true in wetter environments with higher humidity.

Be sure to keep garden soils wet at the time of planting and immediately water the soil around transplants to remove air pockets and dilute any salts that may be present.

Do the same thing when planting from seed. Make sure the soils does not dry between irrigations until you begin to see strong growth from the seeds. Seedlings of many plants are less tolerant to salts, whether they are good salts are bad salts, than the mature form of the same plant.

Mulberry Allergies and Its Elimination

Sneezing? Eyes watering? Headaches? Mulberries are in bloom and have been this past week. If you do not own a mulberry there is not much you can do.However, if you do own a mulberry you can understand where these allergies are coming from and perhaps do something about them other than spraying.

Mulberries produce flowers categorized as catkins. Male and female flowers grow from  respective male and female trees.

Many fruit trees that grow in climates that have seasons (temperate fruit crops) produce their flowers and fruit either on the wood that grew last year (grapes, peaches), or the wood that grows this year (pomegranate) or both years (figs).

Mulberry is a fruit tree. It is slightly different from many of the fruit trees that we know because the tree which produces fruit is a female only. All girl. The tree that produces pollen that pollinates and fertilizes the female flower is a male tree. All boy. Wind is responsible for carrying the pollen from the flowers of a male tree to the flowers of a female tree. Mulberries are either male trees or female trees but male and female flowers are not found on the same tree.

Male mulberry tree ready to flower and release pollen from wood that grew last year.

Female trees are no longer planted much in cities because female trees produce fruit that stain cars, sidewalks, patios and attract birds which love the fruit and poop the same mess.When mulberry is outlawed in a community because of allergies, it is the male mulberry tree that is banned, not the female.

Mulberries pruned so that all of last year's wood has been removed. The primary areas where new growth occurs are at the ends of the major branches.Yes, this is an acceptable pruning practice and not considered "topping" which is unacceptable.

Mulberry flowers or catkins are produced very early in the spring on branches or wood that was produced last year. They are not produced on wood during the current season. If wood that was produced last year on a male tree is removed each year, there would be no male flowers and no pollen.

There is an old pruning technique seldom used anymore called pollarding. Pollinating is a very specialized pruning technique usually established on trees when they are very young. Branches or arms radiate from the trunk. New growth is concentrated at the ends of these arms and is removed every year.

Read a great article published in Australia about pollarding.

Read a more detailed discussion about pollarding

Pollarding can be used on several types of trees to keep them from growing into power lines, allow for more light into the landscape during winter months, conserve water and reduce or eliminate either pollen or fruit by some landscape trees.

I believe pollarding should be an acceptable and encouraged practice of pruning mulberry trees to reduce allergies, save water and beautify our landscapes.

Use Limb Spreaders on Fruit Trees Now to Increase Production

If you have been to any of my pruning workshops you will know the best production from fruit trees comes from branches growing at 45° angles from horizontal. Several fruit trees such as pears and plums tend to grow more upright than this. Frequently their limbs may be at 60° angles from horizontal.

Upright growth of plum in bloom

Limbs that grow more upright than 45° tend not to flower and fruit as much as limbs growing at lower angles. Limbs growing at angles lower than 45° tend not to grow rapidly but will flower and fruit more readily. Bending branches so that they receive more light and grow at 45° angles will improve fruit production of most fruit trees.

Limb spreaders on peach. Spreading the limbs apart to a 45° angle permits more light to penetrate inside the canopy and improves fruit production in the interior of the tree.

To spread limbs that are less than 3 years old to the correct angle use limb spreaders or string to pull them down to the proper angle. Limbs that are older than this will not bend easily and probably will break. On these younger branches the best time to bend them is when their bark is slipping as they are beginning their growth cycle. That time is now, March, and for the next month or so.

Limb spreaders on a young apple tree.

You can make limb spreaders for older trees with 1x2 inch wood notched at both ends. Make some that are 8 inches, 10 inches, 12 inches and longer for different situations. On very young trees some people have used popsicle sticks, tongue depressors, paint stirring sticks, etc. Some people will put a finishing nail in the crotch of this notch to prevent the limbs spreader from slipping. Other people will use string to tie weights to the branches or stake the string to the ground to hold the branch at a 45° angle.

Now is also a good time to bend branches in a different direction. If you have an empty spot in the canopy of the tree explore the possibility of bending a branch to fill this void. Now is the time to do it.

Finishing nail driven into the crotch of a limb spreader. The head of the nail is removed

You can purchase limb spreaders as well.These will come in various lengths but I think you will have to buy them online.

Avocados for the Cold Desert?

Q. I have read that Mexicola avocados are ok in as low as 15 degrees once established. Am I wasting my time trying? Or do I need to grow it in a pot until a certain size so I can bring it inside? Love avocados but don't want to buy something just for it to die.

A. Avocados are a real gamble in the Las Vegas area. If you look around town you don’t see too many which is a good indicator they don’t survive here very well. But you are right. If you are going to try one, it would probably be a Mexican race of avocado such as Mexicola, and planted in a protected location.

A few of the avocado varieties

            The problem is its size. You could keep it pruned below 20 feet which will help keep it from freezing if planted in a warm microclimate and protected from cold winter wind. The other problem is pollination. There is a good chance you will not need a second tree for pollination to produce fruit but you may produce more fruit with a compatible tree for pollination.

            Another option is to plant a dwarf avocado such as Little Cado, a hybrid between Mexican and Guatemalan races. This dwarf avocado can handle temperatures down to about 25° F, similar to many citrus growing in Las Vegas planted in warm microclimates.

Read more about the 3 races of avocado published by the University of California Riverside

http://ucavo.ucr.edu/General/ThreeGroups.html

Farmer Photinia versus Fraser's Photinia

Q. Is there a difference between the red tip Photinia and one I saw called Farmer Photinia?

Fraser's Photinia or Red Tip Photinia demonstrating its name in the spring as new growth emerges.

A. I have never heard of Farmer Photinia. Maybe you mean Fraser's photinia or Photinia fraseri. Red Tip photinia and Fraser’s photinia are the same plant.

Red Tip Photinia

            Most of the Photinia available to us originally come from south to east Asia including China and Japan. There are 2 other Photinia we can sometimes find locally called Chinese Photinia and Japanese Photinia. But Fraser’s Photinia, or Red Tip Photinia, dominates our landscapes in Las Vegas.

Red Tip Photinia trying to survive in rock mulch

            Remember that these plants do not like rock mulch and frequently turn yellow and scorch in 4 to 5 years after they have been planted. Most of this is because the soil has become mineralized and the organic matter, or compost, applied at the time of planting has disappeared over time.

Bird Damage to Citrus Flowers and Immature Fruit?

Q. I have a lemon and a lime tree in my yard. For several years now they have only produced one lemon and one lime. I was told that the birds are probably eating the blossoms but I never see any signs of birds in the yard. Can birds be the cause for only one lemon and one lime in two years?

A. I have heard that before from some people who have citrus but I have never seen it. I think it is anecdotal. Some flowers are sweet and if there is nothing else available perhaps they might but not when other food is plentiful. Different citrus flower and fruit at different times of the year.

The reports I have seen point mostly at sparrows or finches as the culprits. To be sure, you would have to catch them in the act. The only solution I know is bird netting or giving them a chance to eat food they would prefer.

The usual problem with lack of production is freezing weather soon after or during bloom. Even before bloom. Flowers, flower buds and young fruit cannot withstand temperatures below freezing while the tree may not have any damage at temperatures slightly below freezing (lime) or to the low 20's (most lemons).

Another possibility is irregular watering, particularly in the spring and summer months when plants require more frequent watering. Increase the times you water during the April and May months. Use a surface mulch on the soil around the tree to retain moisture around the roots.

Fig Tree Would Produce Figs with More Water

Q. In the small orchard in back of Tule Springs, Nevada, at Floyd Lamb State Park is a huge Turkey Fig that will not produce fruit, only hard little knots. Each tree only has one watering head. Wish you had some pull out there so they could get some major water on that large fig. It tries to produce hundreds of figs each season but they dry out due to lack of water. Thank you so much.

A. Sorry. I don't have any pull there. You are exactly right. there is enough water for the tree but not enough for production of juicy figs. Maybe someone will read this and do something about it. Or maybe they don't want it to produce figs. If they correct the watering problem and no one harvests the figs from that tree at least the birds will have something to eat.