Tomato spotted wilt. Seedling diseases. Aspergillus crown rot. Root-knot nematodes. White mold. Cylindrocladium black rot. If these names catch your attention, chances are good that you grow peanuts for a living or help growers to protect their crop.
These names have more in common than simply their association with peanuts. Each can cause significant yield loss if not effectively managed. With the exception of CBR, the rest are widespread problems wherever peanuts are grown in the Southeast and could be more severe because of a very warm winter and a hot, dry spring. It’s too early to say exactly how our increasingly summer-like conditions will affect diseases in 2017, but it is best to anticipate increased problems with tomato spotted wilt, Aspergillus crown rot, nematodes and white mold this season.
All of the diseases mentioned above, and I include nematodes though they are not truly a disease, have one more thing in common. It is the most important thing: There are management opportunities that are lost once the seed is buried. For white mold, the growers will have additional management opportunities later in the season. But for the rest, the most effective decisions are made as, or shortly before, planting is completed. Today, in-furrow applications impact management of seedling diseases, thrips, tomato spotted wilt, CBR, white mold and nematodes.
A number of products can be used to effectively manage thrips. However, only Thimet (active ingredient phorate) reduces risk to tomato spotted wilt. This is not related directly to “thrips control” but is associated with the response of the plant to Thimet. Thimet likely activates a defense response in the peanut plant that helps to protect it from the virus. Growers who plant prior to May 1, or who choose cultivars more susceptible to spotted wilt (see Peanut Rx), should consider Thimet as one way to reduce risk to spotted wilt.
Germinating peanut seeds and young seedlings are susceptible to attack from a number of fungal pathogens to include Rhizoctonia solani and Aspergillus niger. Fungicide seed treatments are a critical tool to manage seed rots and seedling diseases; nearly all seed is treated with Dynasty PD. Dynasy PD is composed of azoxystrobin, fludioxonil and mefenoxam.
Growers can complement seed treatments and further protect young plants from seedling diseases with an in-furrow fungicide application. The most effective in furrow-spray for stand establishment has been Abound, although Proline also has activity on these same pathogens and Evito is labeled for this use as well. It is unlikely that a grower would benefit from using more than one of these fungicides in-furrow at the same time. The most important factors to reduce impact of seedling disease are the quality of the seed and putting seed in the right soil conditions at the right time.
Proline applied in-furrow is an important treatment for the management of CBR, though this disease has been less widespread in recent years. When very warm weather occurs early in the season, in-furrow applications of Proline also offer some protection from early-season white mold. The extent of the protection is likely less than that provided by banded applications of Proline 3-5 weeks after planting. Decisions to use Proline in-furrow should be made based upon, a) risk to CBR, and b) risk to early-season white mold (although there are effective alternatives for white mold control).
Nematode-resistant cultivars continue to hold up well against root-knot nematodes. However, growers electing to plant a susceptible cultivar like Georgia-06G in fields infested with the peanut root-knot nematode should consider use of a nematicide. Popular nematicides for peanut production in Georgia include Telone II, Velum Total (18 fl oz/A) and AgLogic 15G (7 lb/A). NOTE: AgLogic 15G is NOT labeled for use in Florida! To prevent injury to seed and seedlings, fumigation with Telone II should occur 10-14 days prior to planting and when soil conditions are not too dry (powder) nor too wet (mud). Fumigation with Telone II can provide excellent control of nematodes but does not control thrips.
Growers who use Velum Total do not need to add an additional thrips control product. Use of Velum Total does provide limited early-season management of leaf spot diseases. Growers should be able to skip the 30-day-after-planting fungicide application for leaf spot, UNLESS they have plant on short rotations or plant a very susceptible cultivar like ‘Georgia-13M’ or ‘TUFRunner’511’. Velum Total may also compliment a fungicide seed treatment and help to insure a good stand. Velum Total should be used specifically for nematode and thrips control; however it will also have some benefit for control of seedling diseases and leaf spot.
AgLogic 15G (7 lb/A) is for management of thrips and nematodes. This rate is lower than what was historically used for Temik 15G (10 lb/A ) and additional research will be conducted to compare AgLogic 15G to Velum Total. AgLogic is likely available in limited quantities this year.
In a favorite song, George Jones sang, “I’ve had choices. Since the day that I was born, there were voices. That told me right from wrong.” Peanut growers today have many, often confusing, choices for early-season protection of their crop. It is critically important not to miss the opportunity to manage diseases early in the season. Some treatments will be more appropriate than others; listening to the “voices” from your Extension agents may help you make the best decision.