Influence of Cotton Cultivar and Planting Date on Arthropod Populations

(Field 5A)
Megha N. Parajulee, Andy M. Cranmer, James F. Leser, Padma L. Bommireddy, Ram B. Shrestha, Stanley C. Carroll, and Mark D. Arnold

Fig. 1. Normal and late-planted cotton under the center pivot at Helms Farm.Objective: The objective was to monitor seasonal abundance of Lygus, fleahopper, and arthropod predators as affected by cotton cultivar as well as planting date window.


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.

Cultivar Fleahopper Lygus Predators
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
Planting Date
Normal 1420 b 291 b 1126 a
Late 2169 a 535 a 1119 a
Sampling Method
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

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