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spanish moth caterpillar

Don’t Let the Summer Heat Bug You

Summer rains have begun.  It is hot, muggy and buggy, and to top it all off, the chances of plant disease increases during our rainy season. While this may all seem overwhelming, there are ways to control and even prevent damage to your plants during the summer.hand picking insects off leaves

Summer Plant Pests: Disease

Summer rains and high humidity can cause an increase in fungus and bacteria that can result in disease. Tips to help reduce bacteria and fungus in the landscape include:

  • Monitor rainfall, and cease irrigation when rainfall occurs.
    Sticking to your routine irrigation schedule regardless of rainfall can create too much moisture, resulting in bacteria and fungi and ultimately disease. Place a rain gauge in an accessible area that you can empty easily. If you have an automatic irrigation system, turn it off during the summer months and only run it manually as needed. Learn how to tell when your plants need supplemental watering (For turf, grass blades will appear gray, grass blades will fold in, footprints on lawn will remain visible. For ornamental plants, watch for drooping or wilting foliage). Additionally, an increase in certain weeds may help you determine that there is too much water in that part of the landscape.
  • Avoid installing plants too close together. Plants in humid conditions can benefit from social distancing! Plants that lack space for air circulation are more susceptible to disease. If your plants are too close together consider pruning to create space between them.
  • Learn the types of diseases that may target your specific landscape and/or edible plants. The best time to do this is when you purchase or install new plants. Being armed with this knowledge will help you be prepared for early signs of disease.
Summer Plant Pests: Insects

I see “bugs”; what do I do? First, remain calm. Know that all insects are not harmful in your garden. In fact, we should welcome many insects to our gardens and landscapes because they are part of a healthy environment, and often prey on the very insects that cause plant damage. For this reason, it is wise to avoid a “kill-all” approach to insect control.

Make it easier on yourself! You don’t have to be able to identify hundreds of insect species that visit your plants. However, if you learn to recognize some common signs of insect damage, as well as just a few of the more common types of insects, you can be well on the way to successful management of insect pests.

  • The presence of pest insects can often be predicted, and this works in your favor. Insects love to feast on tender new growth. These are the areas to spot early insect damage. Also, many insects prefer a particular plant species or members of a plant family. Know your plants and learn which insects (if any) that may commonly target your plant. Again, forewarned is forearmed!
  • Many common insect pests loosely fall into two categories: chewers and suckers. Suckers have mouth parts that pierce plant tissues and suck nutrients from the plant. Chewers have mouth parts that chomp on plant tissue.
  • Common sucking insects to become familiar with include aphids, scales, thrips, mealy bugs, and whiteflies. These tiny insects are very common in landscapes. Signs of damage from suckers can be mottled, wilted, or puckered/curled foliage, or leaf tips that appear scorched. Flower buds can be damaged. Advanced infestation can result in foliage covered with a black coating (a harmless sooty mold that grows on the sticky excrement of some of these insects).
  • Commonly found chewers include beetles, grasshoppers and caterpillars (more on caterpillars below). Damage can be ragged edges or holes in foliage, or other missing parts of plant.

Finally, what do you do when you see damage occurring on your plants? A great approach is described in the guidelines of IPM, (Integrated Pest Management). This environmentally friendly approach advises confronting plant damage with the least toxic approaches. Techniques such as hand removal, pruning away infected branches, even spraying insects with a stream of water to disrupt them can often be all that is needed to reduce pests. If further treatment is needed, chemical action can be applied (following all product labels). The least toxic methods are recommended as first-line chemical control (such as horticultural oils, insecticidal soaps, etc.).

Early detection of plant damage in your landscape will save you time, money, and heartache from losing your plants. Grab an iced drink and walk through your garden/landscape frequently, at least a couple of times a week. As you stroll, observe your plants; look at the leaves, buds and fruits of your plants. As you make this a habit, you will learn to anticipate the appearance of your healthy plants and quickly notice beginning problems. Of course, an added benefit of strolling through your yard is the relaxation and peace of being in nature.

This blog post was written by Master Gardener Volunteer Molly Griner under supervision of the Master Gardener Volunteer Coordinator and Residential Horticulture Agent Anne Yasalonis.
For more information, contact UF/IFAS Extension Polk County at (863) 519-1041 or visit us online at The Plant Clinic is open Monday-Friday, 9:00 am-4:00 pm to answer your gardening and landscaping questions. Give us a call, or email us at

If you are not in Polk County, Contact your local UF/IFAS Extension Master Gardener Volunteer Plant Clinic.

The Florida Master Gardener Volunteer Program is a volunteer-driven program that benefits UF/IFAS Extension and the citizens of Florida.  The program  extends the vision of the University of Florida/Institute of Food and Agricultural Sciences, all the while protecting and sustaining natural resources and environmental systems, enhancing the development of human resources, and improving the quality of human life through the development of knowledge in agricultural, human and natural resources and making that knowledge accessible.

An Equal Opportunity Institution.

4 Comments on “Don’t Let the Summer Heat Bug You

  1. What can I do for plants that have white fungi like in your picture. I’d rather not use chemicals as I want to have butterfly’s enjoy. Is there something safe I can use?

    • Judy, It sounds like you have mealybugs. Can you get close enough to the insects to confirm? There is some information in this blog post on how to get rid of them:

      I would suggest trying the method of spraying with water and if that doesn’t work, trying a horticultural soap. Additionally, if the infestation is bad, you can try trimming all of the leaves back. Just make sure to put those infected leaves into the trash and not into the compost pile.


  2. Hey! I was going to do a blog on the Spanish moth (convict caterpillar), which I think is in your banner picture (borer in crinum stem?) on this page….who took that? The adult is beautiful! I’ll have to share pics w you-all!

    • Dougbug, one of our Master Gardener Volunteers took it. Would you like a copy of the photo? Just send me an email!