Biology and management of the cowpea curculio in southern peas

Summary

Cowpea curculio, Chalcodermus aeneus (Boheman), is the key insect pest of southern peas or cowpea, Vigna unguiculata (L.), in Georgia and elsewhere in the southeastern USA. Lack of control of this pest can cause regional southern pea production to collapse.

Situation

Southern pea acreage in Georgia was 86,500 acres in 1951 and declined to a low of 4,311 acres in 1997. The inability to consistently control this cowpea curculio was one of the reasons for the decline since there is a near zero tolerance for infested peas in frozen pack processing. Acreage has been on the rise for the last several years (5,302 in 2007, 6,868 in 2008, and 8,153 in 2009) and along with this has come increased concerns about the cowpea curculio. In 2010 and 2011 multiple reports of curculio outbreaks lead to field tests to evaluate efficacy of insecticides in southern peas. There are no labeled insecticides that adequately control this pest at the current time. Also, there is a lack of a sampling method for cowpea cucurlio that can anticipate outbreaks.

Response

Evaluation of insecticide sprays was made beginning at flowering in 2010 and prior to flowering in 2011 using standard pyrethroids and unlabeled materials. The results indicated that, in either crop, the standard pyrethroid treatments did not provide enough control, only oxamyl (Vydate, currently not labeled in southern pea) significantly reduced stung peas relative to the untreated check in both years across all pea varieties. The traditional methods of pest control include planting more tolerant cultivars (e.g. White Acres), the use of effective and properly timed insecticide applications, and possibly cultural controls to reduce the populations of the curculio at a given site. With the potential loss of pyrethroid efficacy, the main insecticide class used, this pest management program is threatened along with southern pea production in the State. Even tolerant pea cultivars can be damaged under high curculio pressure. Also, sampling is a key component of any integrated pest management program. A new modified Tedders trap has been developed at Tifton which shows promise in providing good estimates of curculio populations in the field. Traps will be critical to determine when curculio populations can be most effectively controlled.

Impact

Acreage of southern peas in Georgia has increased over the last few years and so has cowpea curculio problems. The latest value of the southern pea crop in Georgia (2009) exceeded $12,000,000 in annual farm-gate value. Cowpea curculio losses in 1995 reached as high as 40% of the crop value. That was also the last year of the more recent large southern pea acreage (10,985 acres) before the industry in Georgia collapsed to 4,311 acres in 1997, primarily due to problems with this pest. We must develop a management program for this pest if economically viable southern pea production is to remain in Georgia. We have developed information on the use of oxamyl that can be used to apply for a special local needs label. Also, for the first time, we have a decent monitoring tool for the curculio, the Riley-Modified Tedders Trap.

State Issue

Agricultural Profitability and Sustainability

Details

• Year: 2011
• Geographic Scope: Multi-State/Regional
• County: Tift
• Program Areas:
  • Agriculture & Natural Resources