Set pheromone traps in May to catch peach twig borers
Q: Something is eating small round holes in my first crop of Earlitreat peaches. I was really looking forward to eating those peaches. What could it be? Also, is now the time to put out peach twig borer pheromone traps? damages new growth of these trees when fruit is not yet soft and then moves into softened fruit just before it’s ready to harvest. Another reason I like to harvest soft fruit when it is still hard but full of color.
I deploy pheromone traps beginning the first week of May in our eastern Mojave Desert. I replace the sticky trap part and pheromone once a month until harvest. Contrary to what you might read in the literature, I never sprayed insecticides for peach twig borers or coddling moths for 10 years when I used pheromone traps. But I have caught thousands of peach twig borers and coddling moths using these traps over the years.
Q: I applied Bonide Tree and Shrub Insect Control for borers and miners about six weeks ago. Now my plants are growing weird and possibly dying. Once I saw this problem, I sprayed for diseases and then today for insects. What is going on?
A: From your photos, it looks like the damage to the plant was probably weed killer (herbicide) damage judging from the distorted leaves and dieback. There is not much to do at this point except spray the foliage with water, irrigate and make sure the plants were fertilized in the spring, so they are in their best health to recover as quickly as possible. Then wait and see what happens. There is no magic cure at this point except being patient for three or four weeks.
Let’s cover some reasons why this might happen so it might be prevented in the future. The damage could have originated from you or your neighbors. This type of damage is a common occurrence during the spring and the fall months because these are the most effective times to apply weed killers.
First, never use a sprayer or spray bottle that contained weed killers to spray insects or diseases. You should have two separate sprayers or bottles, one clearly marked and used for weed killers.
Weed killers are extremely difficult to clean from a sprayer or spray bottle once it’s been used for that purpose. If there is some weed killer residue that remains after washing, then you just damaged plants that you sprayed for controlling insects and diseases.
Secondly, you or your neighbors should never spray weed killers when there is wind. If you must use a weed killer, look at the tallest trees in the neighborhood and see if their leaves are moving. If they are, do not spray weed killers. The best time to spray weed killers is early in the morning before the wind has kicked up and it starts to get warm.
The word “warm” takes me to the third rule: Never spray a warm surface or when air temperatures are warm or hot. Landscape rock mulch heats up quickly as soon as the sun comes up. These surfaces reach
150 degrees or more by 9 a.m. on a sunny spring day. When weed killers are sprayed on hot surfaces, they volatilize and move to the neighbor’s yard with the gentlest air movement and can cause plant damage.
Q: Several years ago I purchased a Raywood ash and I have been pruning off infected branches at the beginning of each season. Last week, someone at a nursery suggested I apply a systemic containing imidacloprid and clothianidin as active ingredients to try to get some control. Do you know what the problem is?
A: The problem you are seeing is most likely cicada damage from egg-laying that is now healing. The female cuts a slit parallel along the top of the stem parallel to the branch with her ovipositor (egg-laying machinery). The female deposits her flattened oval eggs, about an eighth of an inch long, stacked up against each other along that slit in a nice row.
If you look at the old twig damage closely, the slit looks like tiny teeth on a saw and that slit is healing nicely. When the eggs hatch a few weeks later, the babies fall to the ground and take into the soil where they feed on tree roots.
The insecticide applied as a soil drench might work because it is systemic. Another option is to apply a soil insecticide drench intended for killing grubs in the soil or eliminating the cicadas on the tree as you see them and before they have a chance to cut a slit and lay their eggs.
Continue to cut off the branches if you want if they are unsightly to you, but the tree will heal fast if it is kept healthy.
Bob Morris is a horticulture expert and professor emeritus of the University of Nevada, Las Vegas. Visit his blog at xtremehorticulture.blogspot. com. Send questions to Extremehort@ aol.com.