Prediction of within field cotton yield losses caused by the southern root-knot nematode with the cropping system model-CROPGRO-cotton

摘要

Cotton yield losses due to pests and diseases, especially those due to the Southern Root-Knot nematode (RKN), have increased from around 1.5% in the 1950s to 4.4% in 2000 across the U.S. Cotton Belt. Understanding the impact of RKN as it relates to local environmental conditions, such as soil texture, on cotton growth and development could improve management. Our goal was to predict yield losses for a producer's field that was characterized by three management zones (MZ) with different risk levels for RKN damage. The impact of RKN parasitism on cotton yield was simulated with the CSM-CROPGRO-Cotton Model. The model was adapted to simulate RKN damage using two strategies: (1) RKN acting as sink of soluble assimilate, and (2) RKN inducing a reductionof root length per root mass and root density. The model was modified with data collected in 2007 from an experiment evaluating RKN parasitism and drought stress. The average mid-season population by zone was entered into the model to remove assimilateson a daily basis. The reduction of root length per unit mass was implemented by modifying the root length to weight crop factor. After modification of the model, it was applied to predict differences in yield (seed plus lint) losses for three MZ of a producer's field for the 2006 season. The simulations indicated that cotton yield was highly impacted by RKN population. Yield decreased by an average of 793 kg/ha (22% reduction) in the zone that had the highest RKN population compared to the zone that hadthe lowest RKN population. In general, the simulated values followed the same trend as the observed values. The results showed that CSM-CROPGRO-Cotton model, after adaptation for RKN specific effects on the rate of assimilate consumption and the root length to weight ratio, can be used to simulate yield losses due to RKN under the conditions of a commercial field.