I’m seeing and hearing a lot of confusion from gardeners over the last couple of weeks. I hope I’m not responsible for any of it, but in the event that I am I’m going to set the record straight on several critical and extremely timely issues.
These are the true facts to consider:
1. The weeds you’re treating for right now (annual bluegrass, rescuegrass and ryegrass) are weeds you cannot see! You are in the primest of prime times right now. You must apply Dimension, Halts or Balan between now and September 7 to prevent germination of the seeds of these weeds. They sprout in the fall, establish their roots over the winter and flourish in early spring. There is no way to eliminate them once they germinate, so treatment at this time is your only hope. Don’t be confused: the product you will be buying and applying will probably be labeled as “Crabgrass Preventer,” but that refers to its spring use. You are not applying it now to stop crabgrass. In fact, you’re not even applying it for crabgrass at all – just for the winter grassy annual weeds.
2. You are not seeing Take All Root Rot or Brown Patch in your lawn right now. I’ve had that asked of me a dozen or more times this month alone. TARR is an April/early May disease. Brown patch doesn’t show up until October’s cool weather.
What you are seeing at this hot time are gray leaf spot fungus and chinch bugs, both in St. Augustine. Gray leaf spot shows up as yellowed grass in irregular washes across the lawn, both in sun and shade. On closer inspection you’ll see diamond-shaped lesions on the blades. We’ve talked about it here this summer – you want to avoid nitrogen fertilizers during hot weather as they promote its development. Use a fungicide labeled for leaf spots in grasses and wait until mid-September for the next feeding.
Chinch bugs cause grass to look dry, then dead in a matter of 5 to 7 days. They will always attack St. Augustine in the hottest, sunniest parts of your yard. You can see the BB-sized black chinch bugs (irregular white diamonds on their wings) where the grass is starting to show their effects if you’ll get down on your knees and part the grass with your fingers. Your local nursery or hardware store has several products labeled for control of chinch bugs. Time is of the essence. They can kill large areas of St. Augustine in just a few days.
3. It is extremely unlikely that you have over-watered any of your plants in the past month. The only way that could possibly happen would be if you have a persistent water leak that is keeping the soil saturated in one particular spot. In such a case you would see moss growing on top of the soil. The soil would have a soured smell and affected plants would be wilted all the time.
Since that’s probably not happening, what is? For every one case of over-watering I do see, I see 1,000 cases of letting plants get too dry. If a plant is wilted and if its soil is dry to the touch, bingo, you’ve figured it out. Water it deeply and see if that doesn’t solve everything. That’s assuming it hasn’t reached what is called the “permanent wilting point,” the place from which it cannot return.
4. New plants that are struggling may not have gotten enough water. This is so sad. Plants that were set out from nursery pots this past spring still have most of their roots in that lightweight potting soil. They dry out much more rapidly than the rest of your landscape. The only way around that is to use your garden hose and water them by hand every two or three days. A water breaker or bubbler makes the task much faster and easier.
5. When you have plants with leaves that are browning at their tips or edges, that’s not where the problem is. It’s much farther down (trunks or roots). It’s the same basic principle that happens when the human body has circulatory challenges. The points farthest from our hearts (toes, fingers, earlobes) suffer from shortages of blood. Leaf margins and tips are the first places to get dry and the last places to get water, so when anything happens to a plant’s root system or trunk to interfere with the water-conducting tissues, it’s reflected in those parts of the plants. You must look for any evidence of damage in those areas.
6. Large-leafed, fast-growing trees are always going to drop a large number of leaves when hot, dry summer weather arrives. You can expect it from mulberries, cottonwoods, silver maples, catalpas and empress trees, among others. Water them deeply to lessen the impact of summer, but they’re still going to drop leaves.
7. Yellowed leaves don’t always signify iron deficiency. True symptoms of iron chlorosis: yellowed leaves with dark green veins most prominently displayed on the newest growth first. Iron is a part of the chlorophyll molecule and as such it is bound within the leaves. Once in place it does not move to new leaves. You treat for iron deficiency by applying iron and sulfur to the soil and spraying iron directly onto the leaves. (Take care not to allow iron products to drift onto painted or masonry surfaces that could be stained.) Sulfur acts to lower the pH which tends to keep iron more soluble for uptake by plants’ roots.
The confusion comes with plants that develop yellowed leaves with dark green veins, but that do so on their older leaves. Those leaves soon drop to the ground as well.