Ground squirrels attack almond crops in orchards
Q: Our almond tree was full this year. However, half of our crop was eaten by something. The nuts are not ready yet. They are still green and so hard you would need a nutcracker to crack the shells open.
My husband picked the rest of the almonds so we at least had something to enjoy. Any ideas as to what’s eating the nut and cracking them open?
A: This is most likely ground squirrel harvesting. Technically I think they are called antelope ground squirrels and they are very common in Southern Nevada. We find them typically at residences near or bordering the desert or large expanses of desert landscaping or open lots.
In almond orchards, ground squirrels can harvest an almond tree overnight. They are very active right now, chewing open the green, hard husk and taking the immature seed.
Seeds right now are soft and sweet, not yet hardened. You will see lots of empty shells on the ground from these critters.
Ground squirrels continue to feed on nuts throughout the season. When the husk splits open, they steal the nuts a lot faster and store them away somewhere. It is usually safer to harvest the nuts as soon as they split open and not leave them on the tree to dry.
I know that these little guys look cute but they can be real pests if they get out of control. They will also steal grapes right out of bunches. Bunches with stolen grapes look just like you think they might look, a bunch with grapes missing here and there on the outside of the bunch.
Control is not easy nor is it any fun. In commercial orchards they frequently use poison bait to help control the population. There are other options such as trapping and relocation.
Please be very careful when dealing with ground squirrels. It is rare but they can transmit the plague from flea bites or bitten directly by the ground squirrel.
Here is some very good information on ground squirrels from the University of California: www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7438.html.
Q: I have an Independence nectarine tree that I have been nurturing for two years. This is the first year I have had fruit. On the fruits I kept I am seeing something that looks like dried droplets of sap coming out of the skin. It is not sticky to the touch. Are you able to determine if I have some sort of blight with the fruit? Will I just need to take this plant out?
A: Your nectarine fruit has damage caused by western flower thrips. This is a very common problem with nectarine fruit here in the valley and elsewhere. Once you see your fruit damaged by this insect, you will see it in future years as well. Be prepared to spray.
Damage to the fruit starts before they are the size of a pea. The only control is to apply sprays to the fruit and leaves to protect the fruit from thrips damage. The most effective sprays are insecticides for organic production, containing Spinosad in the list of ingredients. Follow the label precisely.
If you don’t mind applying an effective conventional insecticide, then look for one containing synthetic pyrethrins, sometimes called pyrethroids. The label must say it is approved for tree fruits. Again, it is very important to read and follow the label for best results.
These sprays must be applied to the fruit and leaves starting very early in the season when the fruit are still very, very small. Sprays must be repeated through the season for total protection. Chances are, you will still see some scarring of the fruit but it will be greatly improved.
Q: I’m having a problem with my Japanese blueberry trees. Some are fine but the two on the end appear to be drying out from the top down. Do you have any idea what’s causing this? The soil is not dry and they all get the same amount of irrigation.
A: The usual problem in damage or death to the top of a tree can be found on the main trunk just below the damaged area. I am guessing something has damaged the tree at that point.
There could be several reasons for the damage. Borers cause mechanical damage to the trunk and shut off the water going to the top. Diseases in this same location can do exactly the same thing.
Because Japanese blueberry is relatively thin barked, sunburn from our intense sunlight can kill the trunk in that location and shut off water to the top. Humans can cause damage to the trunk and shut off its water supply as well.
I think we can rule out pathological diseases in our climate. The two most likely culprits are mechanical damage to the trunk by borers or the same type of damage caused by sunburn.
Inspect the trunk at the location just above the healthy area of the canopy. Use your fingers and see if you can pull away any loose bark. Borers tunnel just under the bark usually on the side toward the most sunlight. This kills that part of the trunk and the bark peels away easily.
If you don’t see bark peeling from the trunk at this location, look for discoloration of the trunk on this side facing the sun. Sunburn to the trunk can happen in one hour of intense sunlight during the midday or late afternoon.
If it is borers there is nothing you can do to raise the dead area back to life but you can protect the tree from extensive borer damage with an insecticide soil drench once a year.
In any case, you’ll be forced to remove the dead top from the tree with a pruning shears or saw this winter. Once you do this, it may open remaining branches for sunburn as well. Give them as much protection as you can.
I would not do it now because the sunlight is too intense and will probably cause even more damage to the lower, healthier part of the tree.
Q: I have a brown area on the bottom of my bell peppers. Any ideas?
A: Brown spots on bell peppers are normally from either of two things: a disorder we frequently see on tomatoes called blossom end rot or sunburn.
If it is on the bottom of the fruit and not in a spot exposed to direct sunlight it is most likely blossom end rot of pepper. Blossom end rot, just like in tomatoes, is normally associated with irregular watering even though it is a nutrient deficiency.
An inch of mulch in the vegetable bed helps to maintain more even soil moisture and less fluctuating of the water content in the plant. A more even soil moisture content has been reported to reduce the incidence of blossom end rot.
The other possibility is sunburn. If the brown spot is on the shoulder of the fruit toward the sun and not the blossom end, then it is most likely sunburn. This is because there is not enough shade covering the fruit.
You will see less sunburn on peppers that are buried deeper inside the canopy of the plant.
With bell peppers in particular we want as much leaf cover over the fruit as possible. Light shade, about 30 percent, over the plants, also reduces sunburn. Mulching the vegetable garden also helps.
Having the garden in a location where it is exposed to morning and early afternoon sun, with shade during the late afternoon, will also reduce the problem.
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.
