Late Blight Early in 2010

The following is an article I have sent to the Mitchell News Journal to be the the June 2 edition. There are confirmed cases of late blight in Florida, Louisiana and Maryland, so be on the lookout for late blight on potatoes and tomatoes.

Vegetable gardeners need to be on the lookout for late blight early during the 2010 gardening season. Late blight gets its name because it normally doesn’t pose a threat until late in the gardening season, but this year late blight has already been confirmed in Florida, Louisiana and Maryland.

You might be asking what is late blight? Late blight is a fungus disease of mainly tomatoes and potatoes. The late blight pathogen is Phytophtora infestans, which in Latin means ‘plant destroyer’. The pathogen can infect foliage, stems, fruit and tubers. The pathogen will show up on the leaves as a black lesion and can have white growth around the outer edge. The infection on the stem will usually occur where a leaf or group of leaves meet the stem and will appear as a brown greasy looking lesion. On tomato fruit, late blight will appear as a dark greasy looking lesion. The pathogen can be spread by wind blown spores and it favors warm moist conditions to multiply. It may overwinter in potato tubers or could spread to our area from developing strains in Florida that stay alive long enough to move up into our area as crops in other states develop.

For gardeners control will take a multi-step process. Gardeners should use clean transplants and tubers, use resistant varieties when available, control volunteer tomato and potato plants, and when there is a risk of late blight occurring use a fungicide program as part of management. Most fungicides work as protectant’s so they must be applied before the late blight fungus infects the plants. If late blight becomes severe the foliage or fruit that rot should be destroyed to eliminate them as a source of spores for plants that aren’t infected.

For help in identifying late blight symptoms contact your local Cooperative Extension Center.

Take a Bite Out of Mosquito Problems

The recent bout of heavy, but needed rain will likely trigger a significant increase in mosquito activity in about 10 to 14 days. In residential areas in particular, now is the time for homeowners to take the initiative to reduce the likelihood of serious mosquito problems around your property before they become reality. Before resorting to insecticide applications, consider a few other critical tasks:

Standing water is the critical item because mosquitoes will not be able breed without it. Permanent bodies of water can pose a more formidable impediment, but most of our problems in residential areas are the result of MMOs or "Man-Made Objects" (yes, we guys will take the blame).

Natural low-lying areas will begin to dry slowly, but make sure you're not contributing to the problem with clogged drainage ditches, tire ruts, etc.

Other water-collecting items such as empty buckets, tires, dishes under outdoor potted plants, and the tarps over boats, equipment, etc. need to be emptied, inverted, discarded or whatever is workable to remove the water.

Have birdbaths? They make great observation posts for watching mosquito larvae in the water. There's no need to add chemicals. Do yourself and the birds a favor and flush out the birdbath. The same thing applies to pet water bowls outdoors (livestock water troughs out in pastures are another issue since they're not always as easily flushed out or routinely maintained).

The time for excuses is over. Get out the ladder and climb up there and unclog those rain gutters. The decaying leaf material and other debris actually attract mosquitoes. If you're planning home improvements, consider gutter guards to divert the debris. Also, make sure that your downspouts direct the water away from the house and not simply create a big puddle along the side of the house. If you have those concrete or plastic splash blocks, make sure they're directing water away from the foundation.

Finally, if you're using rain barrels to collect that precious rain runoff, make sure you have them screened, which helps keep out the junk and the mosquitoes as well.

And while you're at it, get your neighbors to do the same. Mosquito control "takes a village," but it only takes one careless villager to make life miserable for the rest of the neighborhood.

For more information on mosquito control around the home, see Residential, Structural and Community Pests Insect Note ENT/rsc-6 at: http://insects.ncsu.edu/Urban/mosquito.htm.

From: Charles Apperson and Mike Waldvogel, Extension Entomologists