@article{hruska_gould_1997, title={Fall armyworm (Lepidoptera: Noctuidae) and Diatraea lineolata (Lepidoptera: Pyralidae): Impact of larval population level and temporal occurrence on maize yield in Nicaragua}, volume={90}, ISSN={["0022-0493"]}, DOI={10.1093/jee/90.2.611}, abstractNote={Four experiments were conducted in Nicaragua over a 3-yr period to determine the effect of whorl-stage infestations of Spodoptera frugiperda (J. E. Smith) and Diatraea lineolata (Walker) on maize grain yields. The experiments separated the effects of period of infestation from level of infestation. Results from all experiments demonstrated that maize is more tolerant of lepidopteran infestation during early growth stages than at later stages. Infestation during mid-through late whorl caused yield losses of 15-73% when 55-100% of the plants were infested with S. frugiperda. D. lineolata infestations were highly correlated with S. frugiperda. D. lineolata infestations were highly correlated with S. frugiperda infestation. Economic injury levels ranged from 23 to 63% of the plants infested with S. frugiperda and D. lineolata over a range of potential yields, using mean yield reduction from the 4 experiments, and an average 75% insecticide effectiveness.}, number={2}, journal={JOURNAL OF ECONOMIC ENTOMOLOGY}, author={Hruska, AJ and Gould, F}, year={1997}, month={Apr}, pages={611–622} }
 @article{hruska_peralta_1997, title={Maize response to corn leafhopper (Homoptera: Cicadellidae) infestation and Achaparramiento disease}, volume={90}, ISSN={["0022-0493"]}, DOI={10.1093/jee/90.2.604}, abstractNote={To determine the effect that the timing of infestation of Dalbulus maidis (DeLong & Wolcott), a vector of 3 maize pathogens, known collectively as “achaparramiento,” has on stunt symptoms and maize yield, we conducted a field trial in the Sebaco Valley of Central Nicaragua. Achaparramiento has caused severe yield losses in maize throughout Central America. Six periods of D. maidis infestation were created using exclusion cages of finemesh screening. The treatments were natural infestations of D. maidis during 0-10, 10-20, 20-30, 30-40, 0-40 d after plant emergence, and no D. maidis infestation. The treatments were repeated on 3 planting dates. During the season, population densities of D. maidis varied from 4 to 8 per plant for the 1st planting date, from 1 to 3 per plant in the 2nd planting date, and from 2 to 8 per plant in the 3rd date. Planting date had a significant effect on plant height, the number of ears, and the yield per plant, but not on disease symptoms or the length of the ears. The timing and duration of D. maidis infestation affected disease symptoms, plant height, and yield: earlier periods of D. maidis infestation produced more pronounced disease symptoms, shorter plants, and lower yields than treatments with late D. maidis infestation. Plant infested 10-20 d after plant emergence had significantly lower yields than plants infested 30-40 d after plant emergence, and plants infested 30-40 d after plant emergence did not have Significantly different yields from plants that were not infested. The yield reduction was caused by smaller ears, not a reduction in the number of ears. The results demonstrate that a management program for reducing the effects of maize stunting diseases caused by the 3 pathogens should be focused on tactics that reduce D. maidis levels from seedling through midwhorl stage of maize growth.}, number={2}, journal={JOURNAL OF ECONOMIC ENTOMOLOGY}, author={Hruska, AJ and Peralta, MG}, year={1997}, month={Apr}, pages={604–610} }