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

Azalea Lacebug

The azalea lace bug (Stephanitis pyrioides) is one of the most damaging pests of evergreen azaleas. They overwinter as eggs in azalea leaves and begin hatching around now. Control is best targeted early in the season when nymphs are present for two reasons. First, nymphs are easier to kill than adults and if you kill nymphs before they mature and lay eggs you have a better chance of clearing up the infestation. Second, the longer azalea lace bugs are on your plant the more damage they do. On evergreen azaleas this damage sticks around for a long time so plants may be permanently damaged. So scout your azaleas and get those lace bugs cleared up before damage occurs. For more information and control options for lace bugs, consult Ornamentals and Turf Insect Information Note No. 39 available on the Internet at http://www.ces.ncsu.edu/depts/ent/notes/O&T/shrubs/ort039e/ort039e.htm.

From: Steve Frank, Extension Entomologist

Cutworms on Vegetables

We have seen a couple of cases of cutworm injury to vegetables in the last two weeks, and it is a good time to remind growers of the importance of scouting for this potentially damaging pest. Several species of cutworms are found in North Carolina, and they can cause serious damage to a wide range of crops including vegetables in both the home garden and commercial production. Cutworms are most damaging in the spring when they feed on young transplants or newly emerged seedlings. Depending on the species, larvae may be found in the soil around the base of plants or on foliage. Cutworms typically hide during the daylight hours and feed at night or on cloudy days. The black cutworm is one of the most destructive cutworms in North Carolina; it severs plant stems close to the soil surface and will move down rows feeding on multiple seedlings each night. This feeding can result in significant stand losses in a very short period of time.

Cutworms overwinter as larvae or pupae in the soil. Moths emerge in the spring, mate and lay eggs on weedy vegetation or crop plants. Conservation tillage and planting into fields where winter weeds were recently disked increases the risk of cutworm infestation. Destroying winter weeds at least two weeks prior to planting spring crops and managing the crop to ensure good seedling vigor will reduce the risk of losses from cutworms.

It is important to scout seedling vegetables regularly for cutworm damage. Prevention is the first line of defense against this pest, but chemical control is often needed when infestations occur. Refer to the North Carolina Agricultural Chemicals Manual (http://ipm.ncsu.edu/agchem/agchem.html) for cutworm management recommendations in specific crops.

From: Mark Abney, Extension Entomologist

Forest Tent Caterpillar

We most often talk about the Eastern tent caterpillar which seems to be the greater pest in the landscape attacking crabapple, cherry, and related trees. Less common in most areas is its cousin the forest tent caterpillar, which has similar appearance but a broader host range including most hardwood trees such as oak and maple. Historically, there have been some major outbreaks in eastern forests, primarily in the northern U.S. This caterpillar can be distinguished by the “key hole” markings down the back, unlike the continuous strip of the eastern tent caterpillar. The other distinguishing behavior is that they do not spin a tent as much, but rather lay a silk trail that becomes more like a mat on a trunk or branch. For more information, see the U. S. Department of Agriculture Forest Service’s Forest Insect and Disease Leaflet 9 available at http://www.na.fs.fed.us/spfo/pubs/fidls/ftc/tentcat.htm.

Inspect Your Transplants!

Now is the time when many gardeners purchase transplants for their home vegetable gardens. This is perfect timing to go over 3 important tips for selecting the best transplants. Remember the following:

1) A young transplant is much better than an old transplant. A common error made by transplant growers is to start plants too early in the season. When held, transplants become too old and woody and are slow to resume growth after transplanting.

2) Transplants should never have fruits, flowers, or flower buds before transplanting. An ideal transplant is young, growing fairly rapidly, but slightly hardened at transplanting time. It should never be over-hardened or too ‘soft’ when transplanted. Rapid growth after transplanting assures a well established plant before fruit develops.

3) Only purchase disease-free transplants. In the past few years, there have been a number of disease issues on transplants sold at home garden centers, including late blight on tomatoes last year which started a very severe epidemic in the Northeast and Southeast. Although we did not find any late blight on tomatoes at home garden centers in North Carolina, it was confirmed in several other states. Starting your gardening season with infected plants will often involve more plant maintenance, yield loss, and possibly even plant death. Do not purchase any plants that have brown or black spots (lesions) on stems or foliage, or plants that look wilted, have distorted leaves or ones that are off-color (i.e. too yellow). It's not worth your time or effort to start off the growing season with diseased plants. In addition, some pathogens may be able to persist for more than a year in your garden after you introduce them (not all diseases, but some).

From: Kelly Ivors, Extension Plant Pathologist

Boxwood Leafminer

Boxwood leafminer adults will be emerging any day. The maggots can do significant damage to the appearance of boxwood, but they usually do not cause dieback. Because the boxwood leafminer has only one generation of midges per year, treating in April and May with a systemic insecticide may prevent premature plant defoliation. Another application should probably be made in mid to late February of the following spring. The maggots develop in blister-like galls on the current year's leaves. Heavily-infested shrubs may become discolored particularly during the winter. These shrubs also tend to defoliate prematurely. In our demonstrations, Orthene and Merit have both given good control of this leafminer when injected into the soil or applied as a drench. Orthene 9.4% emulsifiable concentrate is actually labeled for leafminers on shrubs. Merit is labeled for leafminers on ornamentals and now being marketed in several homeowner products. Ornamentals and Turf Insect Note No. 16 (http://www.ces.ncsu.edu/depts/ent/notes/O&T/shrubs/ort016e/ort016e.htm) provides information on the biology and control of the boxwood leafminer.

From: Steve Bambara, Extension Entomologist