Plant and stand response to early season insect-induced stress in a model system

Responses of soybean plants and stands to simulated s&edcorn maggot, Delia platura (Diptera: Anthomyiidae), injury were evaluated in field studies from 1983 to 1986 in Iowa. Two aspects of injury, stand reduction and plumule destruction, were considered. Higher crop growth rates (CGRs) and leaf area indexes (LAIs) were associated with higher plant densities. Differences between responses of uninjured and plumuleinjured plants to stand density were noted. Examinations of competition between uninjured and plumule-injured plants indicated that uninjured plants were competitively superior to injured plants. Competitive interactions were influenced by plant density. Phenological delay associated with plumule injury contributed to height differences between uninjured and injured plants, which, in turn, lead to substantial differences in development between injured and uninjured plants. Consequently, unequal competition between uninjured and injured plants was identified as a major consequence of plumule injury.