More Advice on How to Manage Plants During the Heat

            This is the time of year we see a rise in humidity along with a threat from afternoon rains. This rise in humidity and high nighttime temperatures can also bring plant disease problems. You can do something now to prevent diseases before they occur.

Clouds building during summer monsoon in Las Vegas

            The potential for disease on plants is always present. But when the environment favors disease development, their potential becomes a reality. Two plants prone to summer diseases include lawns and tomatoes.

            Three methods used to combat summer diseases are to strengthen the plants natural defenses, improve the environment where they are growing so disease is less likely or use chemicals when “all else fails”.

 

Top picture is summer patch disesae on tall fescue. The bottom is summer patch disease on perennial ryegrass. This disease used to be called "frogeye" for obvious reasons in the bottom picture. This disease loves the heat and loves it more when it is humid and the grass is weak.

            Lawns. Tall fescue is prone to summer diseases if they are not healthy or watered between 6 PM and 2 AM. Summer diseases favor warm temperatures and humid conditions. If your lawn is watered and still wet when night approaches, disease is more likely. Water your lawn between the hours of 2 AM and 5 AM.

            If your lawn has not been fertilized for 2 or 3 months, apply a half rate of fertilizer early in the morning when temperatures are cooler and make sure it is immediately followed with an irrigation. 

One of the "blight" diseases on tomato. But you get the picture. These diseases love the humidity. Open the canopy, keep vines off the ground and wet the leaves ONLY early in the morning.

            Tomatoes. It may feel dry to you but inside that tangle of tomato leaves is a hot, humid jungle. Growing tomatoes upright rather than letting them sprawl on the ground reduces disease problems. Also, thinning the foliage improves air movement, reduces humidity inside that tangled mess, and reduces disease potential.

            Lightly fertilize tomato plants once a month. If you plant them in the ground and never fertilize them, chances of disease problems increase because of poor health.

            Never overdo it. A light application is all they need. Applying too much nitrogen can be just as bad as not having enough.

            Some people like to hand water their vegetables by spraying with a hose. Some people apply liquid fertilizer to the leaves. Do this early in the morning so that “tangled mess” has plenty of time to dry before nightfall.

            When all else fails, then turn to chemical protection. Fungicides for lawns and vegetables can be found at the nurseries and box stores. Make sure to read and follow the directions on the label. Applying more than recommended on the label is not better.