July 21, 2014 Peanut Scouting & Crop Report
GENERAL GROWTH AND COMMENTS Peanut growth continues to show promise of excellent yield for most fields. Most major management decisions regarding weeds, gypsum application and utilization of Apogee is finished. Now is time to manage insects and disease. DISEASE MANAGEMENT As mentioned in the last post, NCSU provides daily forecast and recommendations for foliar fungicide applications. Review of these forecast is found at http://ncsupeanut.blogspot.com/. Applications following this advisory has been proven to reduce the number of fungicide applications as well as reduce the probability of spider mite infestations compared to routine, scheduled applications. One disease worthy of special mention is Tomato Spotted Wilt (TSW). TSW is evident, yet incidence very low, throughout the county. Most management decisions to control TSW have already been made prior to this date. Foliar application of acephate insecticide has shown to reduce TSW since the application decreases the thrip population that spreads the disease. However, it should be noted that this data reflects application BEFORE TSW incidence is evident within a field. After TSW is established wthin a field, data shows no advantage to insecticide treatments. Too, applications of insecticides in early July or August often increase the probability of spider mites. Thus, the decision to apply acephate to reduce TSW, once established is not warranted. INSECTS Typically, most peanut fields do not require application of insecticides for caterpillar pests from July through September. Corn earworms, tobacco budworms, armyworms (fall and beet) are commonly found but do not reach a population high enough to warrant treatment. These pests eat foliage but peanuts can withstand a great deal of damage during this time period before economic loss occurs. Having thus said, all indications are that the season may be one with heavy insect pressure. According to a web post by Dr. Ames Herbert, Virginia Tech University, multiple species of worms may be present. If we experience the same, pyrethroid insecticides will not be effective. Choose insecticides based upon caterpillar identification! Differentiating fall from beet armyworm is relatively easy. A gallery of images for beet armyworm is found at http://ipm.ncsu.edu/cotton/insectcorner/photos/baw.htm and a gallery of images for the fall armyworm at http://ipm.ncsu.edu/cotton/insectcorner/photos/faw.htm. Distingusihg a corn earworm from a tobacco budworm is a bit harder. Generally, the threshold for caterpillar pests (all combined) is 4 per foot of row at this time of the year and will remain at this level until early September when it is increased to 6 caterpillar pest per foot of row. By late September, 10 caterpillar pest per foot of row is required to warrant insecticide treatment.