Carolyn Saft Contributor
As a fifth-generation Floridian, I’ve got to admit—I’m not a fan of the summer heat and humidity. Honestly, I’m just glad I’m not a plant stuck outside in those steamy, sauna-like conditions all day, every day. It always amazes me how weeds and insects seem to love it, and somehow manage to thrive in this weather. Have you noticed that in just a week, little green weed sprouts suddenly grow to be a foot tall? Chamberbitter, spurge and dollarweed go crazy when the afternoon rains and heat kick in. smilax, virginia creeper and grapevines seem to take over shrubs and trees in no time. So, what can we do — retreat and deal with it when it cools off? There are better solutions… First, scout your plant beds early in the morning or late in the evening. Look for weed seedlings and take care of them while they are small. Herbicides work best when the weeds are small, rather knee-high. Try to determine if the weed is a type of grass, sedge or broadleaf, since herbicides are formulated to target specific types. If you are unsure, ask your local UF/IFAS Extension Agent, or send them photos for weed identification. Secondly, watch out for plant diseases, especially with the typical summer afternoon showers. The heat and humidity here in North Florida create the perfect environment for fungi to thrive. Keep an eye out at least once a week for signs of trouble, like black spot, rust or southern blight. Some plants, like cucumbers, watermelon, hydrangeas, lantana and purple coneflowers are especially prone to a fungal disease caused by Corynespora cassiicola. Of course, there are plenty of other fungal diseases out there too, so regular scouting can really help you catch problems early. Limit disease problems by selecting cultivars that are more disease resistant and avoid overcrowding the plants to allow room for air circulation. If possible, avoid overhead watering during periods of drought, and water early in the day so plant leaves have time to dry out. Unfortunately, there is not much we can do about evening thunderstorms, except avoid using plants susceptible to disease or applying preventative fungicides to reduce disease issues. If you do spot diseased leaves, quickly remove those leaves and discard them in the trash—do not put them in your compost pile. Copper fungicides, neem oil, phosphoric acid (Monterey Agri-Fos Systemic), chlorothalonil (Daconil, Bonide Fungonil, Fertilome Broad Spectrum, Hi-Yield, Orhtho Max and Southern Ag), mancozeb (Bonide Mancozeb with Zinc, Southern Ag Dithane) or Myclobutanil (Spectracide Immunox Multi-Purpose) can be used on some fruits and vegetables as well as ornamental plants. Lastly, keep an eye out for insects, such as aphids, that feed on new growth and can cause the leaves to curl, mealybug or soft scale, which looks like a cottony mass or hard tea scale, especially on camellias. All these insects secrete a sticky honeydew substance that black sooty mold grows on. Look for these insects under the leaves and on stems. You can use insecticidal soaps (do not use Dawn liquid detergent — it strips the cuticle layer off the leaves), horticultural fine oil or sometimes isopropyl alcohol to reduce these pests. Use early in the morning or late in the day to reduce contact with bees and avoid plant scald. Even though it’s hot out, try to check on your plants and landscape now and then—it’s the best way to catch problems early, before they get out of hand. I don’t know about you, but I’m already counting down to fall! Carolyn Saft, Horticulture Agent, UF/IFAS Extension Suwannee County, an Equal Opportunity Institution.