Following is some very useful information for cotton and peanuts from Dr. Bob Kemerait, UGA Plant Pathologist:
Protecting cotton from early-season diseases and nematodes – not quite the same as in your peanut
crop (Bob Kemerait):
Many cotton farmers are also peanut farmers. These growers recognize that cotton and peanut crops each need to be protected at planting from seedling diseases and nematodes. They may also recognize that a number of the same products can be used for each crop. Azoxystrobin (e.g. Quadris and Abound), fluopyram (Velum), aldicarb (AgLogic), oxamyl (Vydate C-LV and Return XL), and 1,3-dichloropropene (Telone II) are important tools in the forever battle against diseases and nematodes affecting both crops. Propulse (fluopyram + prothioconazole) can also be used on both crops. These products are appropriate for a couple of reasons. First, disease caused by the fungus Rhizoctonia solani is our most important seedling disease on cotton in Georgia and is also a threat to peanuts. In-furrow applications of azoxystrobin products are effective in the management of Rhizoctonia. Early-season management of nematodes is critical for both crops and the products listed earlier (Telone II, AgLogic, Velum, Vydate C-LV, and Return XL) can be used to effectively reduce damage and protect yield. The “best” product depends in large part on the size of the nematode population and the susceptibility of the variety that is planted.
While there is a shared need for seedling disease and nematode management in both cotton and peanuts,
there are significant differences between the crops as well. First, though Rhizoctonia solani is an important pathogen on both crops, the fungus Aspergillus niger (Aspergillus crown rot) is not a problem on cotton but is a significant problem on peanuts. As resistance to azoxystrobin is developing in populations of Aspergillus niger, this fungicide is less effective in protecting peanut seedlings than it is in protecting cotton seedlings which are not affected by this pathogen. Products such as Velum and Propulse have additional value to peanut growers because the fluopyram they contain is effective against not only nematodes, but Aspergillus crown rot as well. The fluopyram offers some early-season protection from leaf spot diseases. Peanuts are also affected by Cylindrocladium black rot (CBR), a disease that is most obvious later in the season but treatments are best applied in-furrow at planting time. The fungicide prothioconazole (Proline) is an important management tool for this disease, a disease not affecting cotton. Propulse (fluopyram + prothioconazole) is a useful product on both cotton and peanuts, but for different reasons. The combination of fluopyram + prothioconazole, especially if “spiked” with additional Velum (fluopyram) for increased nematode protection, is tool that can be used to fight Fusarium wilt of cotton (a disease of cotton that is often in association with a root-knot of sting nematodes). The same Propulse, again, often spiked with additional Velum, is an effective tool against CBR which is also often in association with a nematode problem.
Nematodes are an important problem on both cotton and peanuts; however, there are significant differences. First, cotton is affected by the southern root-knot, reniform, sting, and Columbia lance nematodes, while peanuts are affected primarily by the peanut root-knot nematode and, to a much lesser
extent, the lesion nematode and, occasionally, the sting nematode. Nematodes affecting both crops are
managed using resistant varieties are available (southern root-knot and reniform resistance in cotton and peanut root-knot resistance in peanut) and the same nematicides are labeled on each crop. Nematodes tend
to be a more widespread problem on cotton than on peanuts, but must be effectively managed on both crops.
Early season disease management considerations are also tremendously important for peanut growers
because of the threat from the Tomato spotted wilt virus. Thrips must be managed on both crops; however
the threat from Tomato spotted wilt leads to many growers choosing to use Thimet (phorate) on peanuts, a
product not labeled for use on cotton. Because we now recognize that the Cotton leafroll dwarf virus can
affect cotton (though we are unclear on the magnitude of the threat), in the future growers may adopt
early-season management strategies (planting date, variety selection, etc.) as they have for Tomato
spotted wilt on peanut.
Both cotton and peanuts are affected by diseases and nematodes best controlled with early-season
management decisions. A number of the management options are the same, or similar, for both crops.
However, understanding the differences, and the REASONS for the differences, can help growers to more
effectively protect each crop and to protect their yield and profit.
If we can be of help to you at Worth County Extension, please let us know!