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ARS Home » Southeast Area » Stoneville, Mississippi » Southern Insect Management Research » Research » Publications at this Location » Publication #392348

Research Project: Insect Control and Resistance Management in Corn, Cotton, Sorghum, Soybean, and Sweet Potato, and Alternative Approaches to Tarnished Plant Bug Control in the Southern United States

Location: Southern Insect Management Research

Title: Grain yield is not impacted by early defoliation of maize: implications for Fall armyworm action thresholds

Author
item BLANCO, CARLOS - University Of Mexico
item CONOVER, KEVIN - University Of Maryland
item HERNANDEZ, GERARDO - Guanajuato Campus Of Cinvestav
item VALENTINI, GISELI - US Department Of Agriculture (USDA)
item Portilla, Maribel
item Abel, Craig
item WILLIAMS, PAUL - Retired ARS Employee
item NAVA-CAMBEROS, URBANO - Instituto Nacional De Investigaciones Forestales Y Agropecuarias (INIFAP)
item HUSCHISON, WILLIAM - University Of Minnesota
item DIVELY, GALEN - University Of Maryland

Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2022
Publication Date: 6/10/2022
Citation: Blanco, C., Conover, K., Hernandez, G., Valentini, G., Portilla, M., Abel, C.A., Nava-Camberos, U., Huschison, W., Dively, G. 2022. Grain yield is not impacted by early defoliation of maize: implications for Fall armyworm action thresholds. Southwestern Entomologist. 47(2):335-344. https://doi.org/10.3958/059.047.0209.
DOI: https://doi.org/10.3958/059.047.0209

Interpretive Summary: Defoliation of corn by abiotic and biotic factors during early developmental stages has produced contrasting impacts on grain yield. Researchers have evaluated natural herbivory and tried different techniques to mimic gastropod, arthropod, and hail damage, the most frequent cause of defoliation in young corn plants. Among numerous arthropod pests of corn, the black cutworm, beet armyworms, and the fall armyworm are the most common defoliators of early-stage corn in the Americas, where several control tactics have been developed for each pest. In this study, we conducted research on corn defoliation with two specific objectives. First, we simulated FAW herbivory during V1-V4 growth stages, and secondly, we compared the effect of fertilization and defoliation on corn yield to evaluate the degree to which such applications could assist the plants in compensating for the potential detrimental effect of foliage removal.

Technical Abstract: The fall armyworm (FAW, Spodoptera frugiperda Smith) now is arguably the most important pest of corn in the world. Corn growers in the Americas have battled this pest for decades, and their control recommendations have been adapted for Africa and Asia, based on contrasting results of the impact on yield when this pest infests young corn plants. Important control decision-making tools such as action thresholds are not completely developed for FAW control, and insecticide applications are still recommended at low levels of infestation in young plants. We manually removed 0, 33, and 66% of foliage when corn had 1-2 (V1-V2), and when it had 3-4 (V3-V4) fully developed leaves. These rates of defoliation did not reduce corn yield when compared with undefoliated plants, regardless of the defoliation timing: V1-V2 or V3-V4. Fertilizing defoliated plants significantly yielded more corn grain than non-fertilized plants, and these obvious results show that smallholder corn growers that can afford investing in either fertilizer or insecticide will benefit more from the former.Our results add to the number of reports that indicate that young corn plants have the capacity of compensating high levels of defoliation without reducing yields.