Tanglefoot and Plant Damage

Q. I recently purchased the product Tanglefoot for ants around my pomegranate tree however after reading the directions, it states not to use it on fruit trees. Is it ok or should I get something else?

Tanglefoot used on Peach tree

A. Tanglefoot is a product that can be applied to the trunks of trees and vines. It is like a petroleum jelly or “grease” that stops insects from climbing the trunk with a sticky barrier they cannot cross.

We have used Tanglefoot on fruit trees with no problems. From the manufacturer, "Do not apply directly to young, thin-barked trees or to bearing fruit or nut trees."

Sometimes Tanglefoot applied to the trunk can cause the trunk to overheat if it is in the sun and scorch and girdle it. It can also prevent thin barked trees from "breathing" through the holes or lenticels in wood that has not yet formed bark.

It can be a problem for young thin barked fruit trees, mostly the stone fruits. Apply to older fruit trees per the label.

Almonds Black On the Inside

Q. I've begun my almond harvest and have found black substance on the inside of some of them. It is almost like soot. Do you know what it is and is it toxic? Should I wash it off or throw them out?

A. You didn’t say if it was inside the nut (kernel) or just on the husk. I am assuming it is only on the husk because this is much more common. If this mold is on the nut, discard these infected nuts and do not contaminate other nuts. This reduces the potential of a mold “toxicity” to humans due to aflatoxins.

Yours is most likely one of the “bread molds” infesting the husk or hull and probably developed due to recent rains and high humidity. The nut is safe to eat if not infected. Normally hull rot, as it is called, is not as common here as it is in more humid climates where it can actually attack fruiting portions of the tree and cause a decline in production.

Hull rot is accentuated if you apply too much water and nitrogen fertilizer to the tree. Let them get a little “hungry” for fertilizer and start applying less water to them 4-6 weeks before harvest (skip an irrigation day). If this problem will probably not continue in future years unless it rains again during nut hardening.

Harvest the nuts, dry them out, remove the husk and inspect the nut when you open it. If the nut is infected, discard these nuts and wash your hands.

Whiteflies Destroyed Vegetable Crops

Q. I am new to gardening in the desert and am surprised at my success thus far!  That is, until the whiteflies came. It is August and they are on EVERYTHING!!  I started with insecticidal soap on the undersides of the leaves and I see dead flies there. I am getting ready to plant all new Vegetable crops for fall but need to get a handle on these flies before subjecting new plants to these insatiable pests.

A. Whiteflies are a very tough insect to control once they get established in the numbers you are talking about. Females lay a couple hundred eggs at a time and these hatch and develop into sexually mature adults in about six weeks.

Whiteflies on pomegranateNoticed they are on the bottom sides of the leaves.

Conventional pesticides have not been very effective on whiteflies due to the development of resistance to applied pesticides. Now we rely on a more integrative approach to try to get a handle on controlling them.

This includes the use of oils and soaps when temperatures permit, yellow sticky boards that are renewed on a regular basis, reflective mulches such as aluminum foil, planting trap crops such as squash, hand picking heavily infected leaves early in the season, hand vacuuming, and others.

Yellow sticky trap in greenhouse.

You need to stay on top of this pest early in the season if you expect some control. Their numbers explode when it gets hot. When plants are still small, remove the bottom leaves close to the ground. These usually get infested first and they are impossible to spray on both top and bottom sides of the leaves which you must do.

Get on a regular spray program at their first sign, alternating with soaps and oils. Spray at least weekly both the underside and tops of the leaves. You will need a backpack sprayer if you have lots of plants or you might consider purchasing a fogger to apply pesticides.

Solo backpack sprayer

Foggers are quite effective but must be used when there is no wind. Use yellow sticky cards supported over the crop and replace it weekly. These can be used to help predict when to spray.

Trap crops that attract whiteflies, like squash, may also help. Squash plants strongly attract whiteflies and help to deter them from infesting other crops in the garden. Sometimes it may be easier to remove severely infested plants and replant.

Crabgrass Control Now?

Q. What steps can be taken this time of year for crabgrass invasion?

Crabgrass, not the readers.

A. It is now August. If you correctly identified your weed as crabgrass, there is nothing that you can do now except remove them by hand or do some hand weeding. Crabgrass will die when it freezes hard this winter. If it is in a location where it does not freeze, or lightly freezes, then it will survive and grow more the following year.

All you can do this time of the year is soak them with water and pull or rogue them out.

You can also burn them back if it is allowed. Propane weed flamers or torches work well if you use them in an area that will not continue to burn. The seed, however, will still be there on top of the soil and unaffected. The seed germinates in the spring around the middle of February in our climate or perhaps earlier if it is warm. I purchased one for weed control on my small farm in the Philippines. The more powerful ones like mine will even weeds that are wet or after a rain. Very important in the Philippines.

Flame weeder I purchased

Pre-emergent herbicides or weed killers can be applied about the middle of January to prevent crabgrass from germinating and getting a foothold. It should be reapplied about six weeks later or when the label tells you to. But this time of the year, all you can do is pull, burn or dig them out.If you buy a pre-emergent weedkiller for crabgrass make sure it lists crabgrass on the label, destroy any crabgrass that survive past the end of January and apply this herbicide by mid-January in our climate.

Controlling Frogeye Disease in Lawns

Q. Can you tell me why lawn grass gets frog eyes and the best way to prevent it? Also why does some of the grass look so yellow?

Summer patch, frequently called frog-eye or frogeye patch.

A. This is the time of year we usually see frogeye disease, or Summer Patch, in lawns. This used to be called Fusarium many years ago, but no longer. The yellowing may be due to a lack of nitrogen or iron fertilizer or both.

This disease is a hot weather disease on tall fescue in the Mojave Desert. It occurs when air humidity increases in the summer months or if we water our lawns early in the evenings.

Consider the disease organism to be present on all tall fescue lawns. The symptoms of the disease appear during hot, humid weather or during a rainy period. The worst scenario is if it rains in the afternoon or early evening and keeps the lawn wet during the night.

If our lawns stay wet for at least six hours at night in July and August, this tends to promote this particular disease. The disease will take about 3 to 4 days to appear when conditions are right.

Apply a preventive fungicide if your lawn has been susceptible to this disease in the past. If it has, you need to plan that it will happen again. Purchase a lawn fungicide that prevents frogeye disease, a.k.a. Fusarium or summer patch and states so on the label.

Apply it to susceptible areas 2 to 3 days after summer rains occur. Follow label directions for reapplication of the fungicide. Lawn fungicides aimed primarily at disease prevention and seldom cure diseases once they start.

Fungicides will stop a disease from spreading once applied but seldom cure it.

Nonchemical control includes aerification of the lawn in spring or fall months. Increase the mowing height or make sure lawns are mowed at 2 1/2 inches or higher. Make sure the irrigation has head-to-head coverage and prevent it from getting water stressed during the heat.

Use organic fertilizers on the lawn including composts and bagged manure products. Compost applied as a fertilizer has been shown to reduce many lawn diseases. Compost should be applied monthly during the growing season. Use mulching mowers and leave the mulched clippings to decompose in the lawn and on top of the soil.
Those of you living in Las Vegas can get compost for top dressing lawns in bulk at Viragrow.
Viragrow website

Globe Willow Is Frequently Short-Lived

Q. I have a five or six year old Globe willow tree that is dying limb by limb.  I just noticed that some limbs are covered with some kind of beetle that are about the size of my thumb. They do fly and are a little green in color. I did started spraying with Sevin insecticide.  Is there something else I can do? 

If you don't know what Globe Willow looks like

The one pictured above is 'Navajo' Globe Willow, popular in the Western states.

A. Globe Willow does not have a terribly long lifespan in our climate. If you look around, you don’t see very many old trees.

Borers are quite common in willow in our climate and cause them to have a short life span. The usual symptom of borers in Globe willow are limb dieback, causing the tree to die further and further each year.

Globe willow is disease susceptible. Slime flux disease is a problem it faces and can attract insects that feed on the sour bacterial ooze that comes from infected limbs. In short, I think you are treating a symptom and not the problem.

I do not suspect that these beetles are associated with the borers but, without a picture, I could be wrong. My best suggestion is to remove it and plant a different tree if you plant one at all.

Horticulture Newsletter for Northeast Clark County, Nevada

Those of you readers that are living in and around East Clark County, Nevada, might consider subscribing to a newsletter that was developed specifically for you by Nevada Cooperative Extension. I provided a link back to its source.


September Newsletter for Northeast Clark County, Nevada

Desert plants: Jojoba

JOJOBA

Andrea Meckley, Certified Horticulturist

andrea.meckley@aol.com

Description:  Evergreen shrub

Mature size: 6 feet tall x 6 feet wide

Water use:  low

Exposure:  all day sun

Origin: Sonoran Desert

Uses:  Hedge, screen, or foundation plant

Hardy:  to 15 degrees F

Despite its scientific name Simmondsia chinensis, jojoba does not originate in China.  The botanist Johann Link originally named the species Buxus chinensis after misreading a collection label "Calif" as "China".  This hardy shrub has leathery grey-green egg shaped leaves and the female plant produces edible nut-like fruit.  Jojoba provides year-round food for many animals, including deer, javelina, bighorn sheep, and livestock. The nuts are eaten by squirrels, rabbits, other rodents, and larger birds. Only Bailey's Pocket Mouse, however, is known to be able to digest the wax found inside the jojoba nut.  The name "jojoba" originated from the O'odham people from the Sonoran Desert who treated burns with an antioxidant salve made from a paste of the jojoba nut.   In large quantities, the seed meal is toxic to many mammals, and the indigestible wax acts as a laxative in humans. Jojoba nuts contain more than 40 percent “oil,” which is actually a liquid wax. The wax is highly resistant to oxidation and is stable at high temperatures. These properties make it a very high quality lubricant, equal to sperm whale oil. Only sperm whale or jojoba oil is acceptable for some industrial applications. The wax is also used in cosmetics. For these reasons and because sperm whales are endangered, jojoba is being developed as a commercial crop in several countries.

Leaves of Crepe Myrtle Yellowing

Q. The leaves of my crepe myrtle are turning yellow some show signs I think of a specific mold on underside of the leaves. Please advise in your usual expert advice.

A. When yellowing occurs at the tips first it usually indicates a salt problem. This is possibly due to a lack of water or not enough water applied during an irrigation. It is also possible water is not delivered often enough so the soil becomes too dry between waterings. It is also possible it might be watering too often and not letting the soil dry between waterings.

Crape Myrtle growing at the research center with wood mulch, annual applications of complete fertilizer, iron EDDHA and foliar application of Miracle Gro

Look closely at your watering habits. If you are watering by drip make sure you put lots of gallons down every time you water. For trees this is gallons of water applied each time. The number of gallons depends on the size of the tree. As the tree gets bigger it needs more water applied at each irrigation. NOT watered more often.

Make sure when you water that it is not daily or even every other day. This time of year every three days is adequate but put enough gallons down, not a small amount.

Estimate how much water is delivered each time you water. You can use the chart below if you do not know the gph (gallons per hour) of your drip emitters. For instance if your drip emitter delivers 10 ml of water in 9 seconds then you have a 1 gph emitter. Increasing the total water applied will flush salts from the tree.

Number of seconds to deliver gph (3600 seconds/hr) (3785ml/gal, approx. 4000)

Gph     10ml     20 ml    30ml    40ml     50ml    60ml    70ml    80ml    90ml    100ml
¼           36 sec. 72           -           -            -           -           -           -          -            -
½           18       36        54         72
1            9         18        27         36           45       54         63         72
2            4.5       9         13.5      18           22.5
3            3          6           9         12           15
4            2.25     4.5        6.75     9            11
5             -
6             -
7             -
8             -
9
10           -            -            -           -           4.5      5.4         6.3       7.6        8.1       9.0

If you suspect you are watering too often then increase the number of emitters (this way you do not need to increase the minutes). Increasing the minutes means everything else will get more (or too much) water.

If you suspect you are not giving enough water each time then flush the soil with water several times to remove excess salts and rewet the rootzone deeply. Put a hose at the base of the tree and let the hose run very slowly around the tree near the emitters for several hours. Or build a donut around the tree and fill it several times a few days apart. Or buy a small inexpensive sprinkler that goes on the end of the hose and let it run for 15 to 20 minutes. Repeat every other day three or four times to flush salts.

This could also be from a lack of organic matter in the soil IF the tree is surrounded by rock mulch. Buy some decent compost and apply it to the rocks under the tree and water it in thoroughly. Do this two or three times this fall and repeat it in the spring.

Plum Tree Murdered by Borers

Q. I have murdered my 5 year old Santa Rosa plum. The borers have finished it. I treated the tree for iron twice earlier in the spring, and It never seemed to help, I now see why. They are in every branch, and looks like the main trunk. I had white washed as you suggested, but I should have reapplied every year, since it faded some, and of course the tree grew. I have learned a valuable lesson, and I feel terrible for the loss of my tree. Thank god, I had a bumper crop last year, hopefully I have enough jam to hold me a few years until a new tree takes shape. Thank you so much for years of tips and tricks for our garden.

Santa Rosa plum ripe

A. So many borers as you stated is an indicator that perhaps the branches were getting overly heated and burned by the sun. Always keep a full canopy to shade the limbs and trunk. Pruning fruit trees in the desert is an art. It is finding a fine balance between removing enough and removing too much wood from a tree.

Sap oozing from cut limb on plum. Sap oozes freely from damaged limbs on plum. This is a defense mechanism and when working properly drowns any infesting insect with sap.

Never prune so much that it opens up the canopy for sunburn to the limbs. Mulch the soil which helps keep a full canopy and dig out borers as you see them causing sap oozing from the trunk or have limb dieback. I will do this in the winter time when all the leaves are gone and it is easy to find damaged limbs.

Selecting Crabapples for the Desert

Q. I am hoping to plant two semi -Dwarf Crabapple trees on the west side of my house. Could you please tell me which cultivars will do well here? I am looking for crabapples that are good for raw eating, jelly, and apple butter. I also need to know which are good for cross pollinating each other.  Also, does our local nursery stock these in the fall and spring for planting, or will I need to order them off line?

A. I don't like the idea of putting a crab apple in a Western exposure in our hot desert environment. You run a very big risk of sunburn on the limbs and borer infestations due to the sunburn.

I have never done any trials with crabapple here so Information is limited. I did contact Tom Spellman at Dave Wilson Nursery in California and he confirmed that Dolgo has done well under desert conditions and the fruit has performed well under our conditions. It is an old variety with good fruit and is self-fruitful so you don’t need a pollinator. 

dolgo crabapple from Dave Wilson nursery

Dolgo crabapple is a good pollinator for crabs that need pollinators. I would start with this one. There are some crabs at Gilcrease but I don’t think they know the variety. It is very possible that some or all are Dolgo. Try to choose varieties that have fruit which mature during cooler times of the year for best flavor.

Texas Sage Outgrowing Its Space after Two Years

Q. We have three Texas Sage bushes that are about two years old and doing very well – so well in fact that they are outgrowing their area. I have seen these plants where they have been trimmed back and they look very good. Is it okay to do this without harming them, and if so, should I wait until they go dormant?

A. Regarding your Texas Sage, there are varieties that are smaller than others. Perhaps it might have been better to select one of the Texas Sage which are smaller to begin with so you wouldn't be faced with this so early in its life. 

Texas Sage or Texas Ranger can be pruned with a hedge shears but really should only be sheared this way if they are intended to be in a hedge. If you intend to use a hedge shears on these plants expect them last about five years before they get really woody at the base and don't have much foliage anymore. 

Larger Texas sage pruned with a hedge shears

This may not work for you if these plants are placed into a location where you need to keep them small. But the best way to pruned them is by removing two or three of the largest stems at the soil level. The idea is to continue to remove the oldest wood from the base of the plant every couple of years. 

This keeps the plant juvenile and doesn't interfere with its flowering. Hedge sharing is usually done when there has been new growth which results in removal of the flowers before you can enjoy them.

Vinca Yellowing and Growth Is Stretching

Q. Our Vincas are in pots and have done very well all summer. We have noticed they are starting to be tall/ spindly, and the leaves are beginning to turn yellow. They have been watered three times per week with an auto irrigation system, supplemented occasionally with Miracle Grow from a watering can. Is it the end of the growing season for them, or is there cure?

If you don't know what Vinca looks like

A. The usual problems with Vinca are soil related problems, not enough light and watering too often or the soil not draining well.

Vinca likes to grow in a soil that is well amended down to a depth of about 8 to 12 inches, in full sun and fertilized with a high nitrogen fertilizer once a month. If they are in full sun then your soil is probably running out of organic amendment and you are losing pore spaces in the soil.

The addition of compost to the soil at planting time down to a depth of at least 8 inches is necessary at the time of planting. If you don't add enough compost to the soil, the soil spaces that are created by the compost and soil mix begin to collapse.

As these pore spaces collapse, less aeration reaches the roots and water no longer drains through the soil like it used to. There is not much you can do about that now. It really has to be added at the time of planting. The soil will continue to collapse more and more and then you will start to see isolated plants die.

Upon close examination these plans will have died from root disease or collar rot which is a rotting that occurs right at the soil surface. The other possibilities are lack of light reaching the plants and not fertilizing them on a regular monthly schedule.

You have nothing to lose so try adding a complete fertilizer like Miracle Gro or Peters and see if they perk up. That will not, however, cure a problem if there is not enough sunlight.