Recent rain, humidity may have caused mold on almonds
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 four to six weeks before harvest (skip an irrigation day). 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.
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 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.
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.
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 both the underside and tops of the leaves at least weekly. You will need a backpack sprayer if you have lots of plants or you might consider purchasing a fogger to apply pesticides.
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.
Q: What steps can be taken this time of year for crabgrass invasion?
A: If you identified it as crabgrass correctly, there is nothing that you can do now except remove them by hand. 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.
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.
Q: Can you tell me why lawn grass gets frogeyes and the best way to prevent it? Also why does some of the grass look so yellow?
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 three to four 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, aka Fusarium or summer patch, and states so on the label.
Apply it to susceptible areas two to three days after summer rains occur. Follow label directions for reapplication of the fungicide. Lawn fungicides aimed primarily at disease prevention 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 2½ 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.
Q: I have a 5- or 6-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 is 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?
A: Globe willow does not have a terribly long life span 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.
Bob Morris is a horticulture expert living in Las Vegas and professor emeritus for the University of Nevada. Visit his blog at xtremehorticulture.blogspot.com. Send questions to Extremehort@aol.com.
