It’s wet, hot, and humid during the dog days of summer, and that creates the perfect environment for a host of diseases in our gardens and landscapes. Here’s what’s happening locally so you know what to keep an eye out for.
We’re seeing a wide mix of issues across many garden crops. Diseases like powdery mildew, Alternaria leaf spot, Pythium root rot, Southern stem blight, and even nutrient deficiencies are appearing on multiple plant hosts. With these high temperatures, you may also notice poor fruit set, especially on tomatoes and squash.
Here’s a closer look at specific crops:
Basil is battling downy mildew.
Beans are showing anthracnose, Cercospora leaf spot, and Rhizoctonia rot.
Cucurbits such as squash, cucumbers, and watermelon are facing powdery and downy mildew, anthracnose, Fusarium wilt, and gummy stem blight.
Peppers are dealing with bacterial spot and blossom-end rot.
Sweet corn may show signs of corn smut.
Tomatoes are facing a real gauntlet. Issues include blossom-end rot, bacterial diseases, leaf spots, wilts, early and late blight, root rot, leaf roll, fruit cracking, Tomato spotted wilt virus, and even magnesium deficiency.
Many of these diseases can be managed with a copper fungicide. Always read and follow the label when using any pesticide.
Looking at herbaceous ornamentals, including perennials and bedding plants, you may notice signs of powdery mildew, Alternaria leaf spot, and bacterial leaf spot. These can also be treated with a copper fungicide. Begin applications early and repeat every 7 to 14 days to help stop the spread.
In the general landscape, you may spot cicada killers buzzing low to the ground. These large wasps are mostly harmless. Males patrol while females dig nests. Green June beetles are beginning to target ripe fruit.
And for those multi-plant pests, be on the lookout for the following:
● Planthopper nymphs, which are easy to spot this time of year.
● Fall webworms forming webs in trees.
● Japanese beetles are feeding, especially on grapes and rose bushes, and laying eggs. If you’ve had issues with grubs before, now is the time to apply a grub treatment (Merit® and Mach 2® are two preventative pesticides that can be applied).
● Bagworms, which are beginning to show up in evergreen shrubs. Visit us at caldwell.ces.ncsu.edu or call 828-757-1290 for any garden/landscape questions you may have.