Common Summer Problems Including Insects and Diseases

  • Difficulty Rating: Beginner
Common Summer Problems Including Insects and Diseases

During summer, especially in southern parts of the country, plants are stressed nearly to their breaking point due to drought, heat, disease and insects.

To identify which problems are your worst, examine leaves and stems. Heat and drought stress will show up as burned or drooping foliage, but may also indicate other problems.

Roses face a host of problems, but the two most common ones in my summer garden are blackspot and spider mites. Blackspot is pretty self-evident, with its namesake showing up on leaves.

Black Spot

Eventually, the same leaf will turn yellow and then drop to the ground. Once a leaf has blackspot, it cannot be reversed. Instead, the leaf should be destroyed and not composted to prevent spread of the disease. In more humid climates, powdery mildew can be as troublesome as blackspot, but in my part of the country, it is only evident in spring when we have rain. Certain roses have better disease resistance than others, and the best way to combat disease is to plant these cultivars unless you want to implement a spray regimen. There are natural fungicides, but not everyone agrees on their effectiveness and environmental changes, so Iíve come to rely upon disease resistant cultivars instead.

Spider Mites

Not truly insects, spider mites are tiny sucking creatures related biologically to spiders, which feed on plant cells. They are not exclusive to roses, but during drought conditions, spider mites seem to love them best. Lacewings and lady bugs (lady beetles) eat spider mites as do predatory mites like Phytoseiulus persimilis. If you see spider mite damage on a particular plant, try ejecting them with a strong blast of water. Be sure to spray under leaf surfaces also, but do so in the morning when temperatures are cooler. Insecticidal soaps and horticultural oil also work, but shouldnít be used with current high temperatures.

insects, ladybugs

A garden with a healthy insect population of lacewings, lady bugs and other natural predators helps mitigate the 'bad' bug population. You can increase the beneficial insects in your garden in two ways:

  • Not spraying with insecticides; and
  • Growing nectar rich plants. Native plants often fall into this category.

Another voracious insect is the grasshopper. Grasshoppers are difficult to control, and they are a particular nemesis during drought conditions. There isn't much to be done this summer, but next year, in early spring, spray water throughout the garden and sprinkle NoLo™ bait on leaves. According to the Biocontrol Network, NoLo™ bait is a grasshopper suppression bait, filled with Nosema locustae spores, which is "non-toxic to humans, livestock, wild animals, birds, fish, or life forms other than grasshoppers and species of insects closely related to grasshoppers" like crickets. Although it is pricey, I only use it once in spring, and usually only every other growing season to keep grasshoppers in check. Birds, lizards and rodents also eat grasshoppers.

Because plants are summer stressed, build up their immunity by giving them a natural, water-soluble food. I spray plants with foliar fertilizer during the summer months about every two weeks. With such high temperatures this summer, I’ve been forced spray very early before the sun is fully up, and I drench the soil around plants avoiding the leaves as much as possible. Unless leaves dry, water droplets magnify and burn them.

For much of the country, it’s been a long, hot summer. A month or two, and it will be over, but now is a good time to get out early into the garden and check up on your plants to have a better fall show.