Are Your Trees Under Attack from Summer Pests?
July 13, 2016
Intense heat and humidity are just a reality of summer life in the Dallas and Fort Worth areas. Our plants are wilting, and so are we! Even though we can often receive a lot of rain through the spring months, it tends to stop abruptly when temperatures reach their hottest. That can mean your trees go from receiving too much water in spring, to not enough in summer. It’s also easy to forget that our trees may need supplemental water in summer after all that spring rain.
When trees are weakened from heat or water-stress, they become much more susceptible to infestations of pests. To make matters worse, the very wet spring created a prime breeding environment for many common pests. Now’s the time to keep your eye out for certain bugs that can make life hard on your trees.
Whiteflies are a pest that tend to show up on trees, shrubs and other ornamental plants suddenly in spring and summer. You might first notice them when you see a cloud of small white flies appear as you walk by a tree or a wind flows through leaves. These insects are tiny but you can often see them on the undersides of leaves. They multiply quickly in warm, humid weather so be sure to notify your arborist the moment you see them. Having trees inspected in spring or summer can nip an infestation in the bud.
Caterpillars infestations in summer can cause big problems for trees if they are not kept under control. Because these leaf-eating pests feed in large groups, they can quickly defoliate your trees, stunting their growth and vigor. In spring and early summer, female moths deposit eggs in tree limbs and trunks that hatch the following spring as new, tender foliage is emerging. If we can detect an infestation early enough, we can use a non-toxic biological control such as discs of live Trichogramma wasp eggs. These microscopic predators devour web larvae, leaving humans and pets alone. We also control tent caterpillars with Bt (Bacillus thuringiensis), deadly to caterpillars, but harmless to birds, fish, pets and people. More on tent caterpillars here.
One of the most common pests you’ll find on stressed trees, and other landscape plants, are aphids. They are most commonly found on crapemyrtles, post oaks, bur oaks, and American elms. While these pests are tiny, they can cause a large amount of damage to an already stressed tree. Aphids use sharp mouthparts to suck moisture and nutrients from tree foliage. They also leave behind a sticky combination of excrement and waste called honeydew that can attract other pests. Trees appearing to lose their vigor along with blotchy damage to the leaves could mean you have an aphid infestation. Keeping trees properly watered, fertilized and maintained is your best defense against aphids. More on aphids here.
Healthy, well maintained trees are always better able to tolerate common pest problems. But even healthy trees can suffer damage when infestations are big enough. Know that there are many natural and Eco-friendly means to controlling these insects when treatments are necessary.
It may seem counter intuitive, but late-winter is often the best time to treat trees and large shrubs to prevent many common pest problems from getting out of control in spring and By applying horticultural oils during the cooler months, we can suffocate insects that survive through winter by hiding in your tree’s cracks and fissures.
The horticultural oil we apply is approved by Organic Materials Review Institute (OMRI) and is safe to use around birds and animals and does not harm reptiles. When applied at the right time, these oils can significantly reduce pest infestations during the warmer months so you don’t have to use stronger pesticides to control them if an infestation occurs.
Posted: July 13, 2016