Ask a Master Gardener: From brown, patchy lawn tips to grape growing

Q. What is the best method to fill in bare spots on a fescue sodded lawn, e.g., fill in with patches of sod, manually reseed the spots, use a commercial all-in-one patch, etc.?

A. September is the best time to either lay sod or reseed, so a timely question. Laying sod will give faster cover, and reseeding will be less expensive. If the patches to fill in are oddly shaped, then sod may be annoying to cut and match. If you purchased a specific type of sod, you may want to reestablish with the same type (tall turf type fescue versus Kentucky bluegrass) if you want a uniform look. You can even try to find the same specific variety. Otherwise, just match the grass type to the sunlight level, sold as sun or shade mix. I would avoid commercial patches, as they often have a lot of annual grass to give quick cover. Scratch the bare spot aggressively with a rake, then sprinkle the seed. Then very lightly rake or even use a broom to smooth over the soil. Keep soil moist for the next two weeks by watering every other day, or daily if very hot and dry. A sprinkling of straw or other similar mulch will help with this. Sod should be watered similarly.

Q. What causes brownpatch on cool-season lawns, and what can I do to prevent it?

A. Brownpatch is caused by a fungal pathogen (Rhizoctonia solani) and affects cool-season lawns, with tall turf type fescue being most at risk. It favors warm temperatures with high humidity. The typical start of brownpatch season is June, and more rain makes it worse. So this year it was about as bad as it could be, even making the local news on both TV and the front page. And with all the rain it lingered into July. A good hot and dry spell often sets it back. The disease generally stops with cooler weather in the fall.

Preventing it has three basic options. First, avoid solid stands of tall turf type fescue. So if overseeding grass in the fall, consider adding or using mixes with Kentucky bluegrass, fine fescue or perennial ryegrass. Second, avoid any nitrogen fertilizer after April, until the fall. When nitrogen is added in warmer weather months, this nutrient causes the grass to grow soft and lushly, which favors the disease. The worst thing to do (which some people are prone to doing) is put nitrogen on the lawn following a rainy spell in June "because the grass is a little yellowish." Yes, it greens the grass up, but you just threw fuel on the fire!

The last option is using a fungicide to prevent the disease. The tricky part is applying it before the disease starts, but not putting it on too early. An application in early June would normally time about right. Read the label to make sure it is effective on brownpatch, and reapply in the time period recommended.

Q. My grapes turned black and all fell off this year. What causes that and how do I prevent it?

A. That description matches the most common disease that plagues home gardeners, commonly called "black rot." It is a fungal pathogen that grows on the leaves, flowers and finally fruit. Warm, humid weather aggravates it, especially when coupled with rainy weather. We had the perfect brew this year!

Prevention starts with correct pruning and trellising, which will allow the fruit to be more open, and thus get better airflow, drying off quicker following rain and dew. This is addressed with a University of Missouri Extension publication "Home Fruit Production: Grape Training Systems." What I frequently encounter in grapes that have become overgrown (perhaps ignored a few years) is foliage too thick and branches intertwined. This takes some work to untangle and work through. Once the plants have lost their leaves, it is easier.

For consistent production, and certainly in a year like this, one should apply a fungicide to prevent the disease. The most effective product available to a home gardener is Spectracide Immunox (do not get the Immunox "Plus" formulation, as it is not labeled for grapes). Critical application times are when shoots first start growing, when flower clusters form, at flowering, and two weeks later (a fourth application may be needed in very rainy years). If one grows a lot of different grape varieties, then Mancozeb can be used up until flowering, and this other product after that.

The local Master Gardener hotline is staffed from 12:30-4:30 p.m. Tuesday and Friday afternoons through the end of September; call 634-2824 then or anytime to leave a message. The Central Missouri Master Gardeners are a volunteer group of 191 members, 122 of whom are Cole County residents, who maintain 11 beautification sites in Cole County. Master Gardeners must complete a basic training program of at least 30 hours of horticultural training including landscaping, lawns, vegetables, flowers and fruits, as well as 30 hours of volunteer service.

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