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Swarming and Biting Gnats, Tree Leaf Diseases, Master Gardener Plant Sale
By John Fulton

[May 02, 2016]  Swarming and Biting Gnats Have Returned - Spending some time outside over the weekend and early in the week, it seems the dreaded gnats have returned, and at least some of these are the early buffalo gnat populations. The small flies, or gnats, are hatched in clean, running water. This is one indicator our water protection plans are succeeding. They will continue to hatch until water temperatures hits about 75 degrees. They will also travel up to 10 miles in search of a food source, meaning blood.

Male buffalo gnats feed on nectar while the females feed on nectar and blood. These insects can produce serious welts when they decide to bite. They tend to be worse during the day, and are seldom a problem inside buildings. In addition to people, they tend to attack birds. Young poultry and wild birds are especially vulnerable. Some poultry insecticide treatments, such as insecticide dusting, will help control the gnat populations.

Control is difficult. Sprays of malathion, permethrin, or bifenthrin (or area fogging) will help with controlling the buffalo gnats when outdoor activities must be held in infested areas. Of course, their robust travel habits mean area treatments will be short-lived. Dusts of permethrin will also help with outside poultry operations. Repellents of DEET, citronella, vanilla, and some of the other plant based repellents may also provide some relief. It seems like the vanilla, or a commercial product such as Buggins or black fly ointment, are much more effective than the DEET. Remember, only the females bite and the males swarm your face. When the bite occurs, a chemical is injected to help with blood flow. This is often the reason for the painful welts, usually on the face. Children also seem to be bitten, and affected, more than adults. The gnats seem to be attracted to white clothing, while Navy blue seems to be the least favorite color of the buffalo gnat.

Tree Leaf Diseases

One of the normal scourges of spring has hit us again. This is the group of fungi collectively known as leaf spot fungi. Common ones include anthracnose and apple scab. Anthracnose starts as dead leaf areas between leaf veins, or on the tips of leaves. When severe enough, leaves will fall. Several of the infected trees have actually had the leaves turn completely black already. It is much more noticeable on one side of many trees as well, due to air movement carrying the disease and drying out foliage quickly. The good news is that it rarely harms trees. If enough leaves drop, a new set comes out in 4-6 weeks and we start all over. The next set of leaves may also get the disease, but they may not. Infection can continue with weather favorable to the disease, and when nighttime temperatures stay under 65 degrees. Treatments when you see the symptoms of this disease are simply wasted time and money.

Apple scab is a disease similar to anthracnose, and can cause premature leaf drop in apples and crabapples. If you are on a regular spray schedule for fruit trees, it should prevent most of the problems. You could also spray crabapples this way, but you would have to weigh the cost and benefit since no fruit production is involved.

As a reminder, spray programs for disease prevention in fruit trees should be applied every 10-14 days after the bloom period is over. It should be stressed that these are preventative programs, and not curative. These programs then continue until roughly two weeks before the fruit is ready to harvest. 

Master Gardener Plant Sale

The 15th annual plant sale by the Logan County Master Gardeners is scheduled for Saturday, May 14. It will be from 9:00 a.m. until 11:00 a.m. in the Logan County Special Event Building (located across from the Fair Secretary’s Office on the South end of the fairgrounds). Types of plants for sale include perennials, annuals, heirloom tomatoes, peppers, ornamental grasses, houseplants, and a limited number of shrubs. There are no early sales available.

[By JOHN FULTON, COUNTY EXTENSION DIRECTOR SERVING LOGAN, MENARD, AND SANGAMON COUNTIES]