Megha N. Parajulee, Andy M. Cranmer, James F. Leser, Padma L. Bommireddy, Ram B. Shrestha, Stanley C. Carroll, and Mark D. Arnold
Methodology: The treatments consisted of four commercial cotton cultivars, Stoneville 2454R, Paymaster 2326RR, Paymaster 2145RR, and Paymaster 2167RR, and two planting dates, May 7 and June 7 in a randomized complete block design with four replications. Planting date treatments included a timely planting (within the optimum planting date window recommended for the southern High Plains) and a late planting date that coincided with the replanting cut-off date for the region. Weekly arthropod sampling began on June 17 and continued through the growing season. A vacuum sampler (2-cycle backpack aspirator) was used to monitor arthropod populations in all plots. Five different sampling methods, vacuum sampler, sweepnet, beat bucket, drop cloth, and visual inspection, were used only in the PM 2326RR plots to evaluate the sampling methods for insect monitoring. Sample units for each sampling method varied; the sample counts were converted to numbers per acre.
Results/Summary: Seasonal average Lygus and fleahopper numbers varied significantly among cotton cultivars. Paymaster 2326RR supported significantly higher number of Lygus and fleahopper when compared with the other three cultivars evaluated. There was no significant difference in seasonal predator numbers among cultivars.
Planting date significantly affected total seasonal numbers of both Lygus and fleahoppers in our study. Late planted cotton had significantly higher numbers of both fleahoppers and Lygus compared with timely planted cotton. The planting date had no significant effect on the total seasonal predator count.
The efficiency of the sampling method varied with the arthropod. The beat bucket method captured the greatest numbers of Lygus and predators. The visual method accounted for the most fleahoppers.
Table 1. Average seasonal arthropod counts per acre recorded in cotton cultivars, by planting date and sampling method, TAES, Helms 2002.
|ST 2454R||778 b||282 b||1171 a|
|PM 2326RR||2761 a||588 a||1037 a|
|PM 2145RR||1242 b||314 b||1258 a|
|PM 2167RR||946 b||204 b||1024 a|
|Normal||1420 b||291 b||1126 a|
|Late||2169 a||535 a||1119 a|
|Beat Bucket||4841 b||2009 a||47155 a|
|Sweepnet||1299 c||383 b||1742 d|
|Drop Cloth||934 cd||357 bc||9819 c|
|Vacuum||512 d||113 c||927 d|
|Visual||6717 a||182 bc||27828 b|