Corn Recovery from Early-Season Frost

Abstract

Early season frost injury can be devastating to corn (Zea mays L.). Such an incident occurred on 28 May 1992 injuring thousands of acres of 3- to 4-leaf corn in south central Nebraska. Damage ranged from slight to complete defoliation. Since there was limited information available on management options to make recommendations, we compared three alternatives: control (no treatment), clipping the plants above the undamaged stalk (2.4 to 3 in.), and replanting. Three field sites with different levels of defoliation (55, 70, 100 %) were selected to compare these options. Unfavorable weather conditions for plant recovery prevailed for several days following the frost. Plants continued to die for several weeks at two of the sites. Plant death was associated with the development of soft rot at or just above the growing point. A bacterium, Pseudomonas fluorescens, was isolated from affected tissue and was used in greenhouse studies to successfully carry out Koch's postulates demonstrating this organism as the causal agent of the disease. Pseudomonas fluorescens is not considered a pathogen of corn but environmental conditions following the frost apparently allowed it to become opportunistic and behave as a facultative parasite. All treatments yielded similarly at the site with intermediate damage (70 % defoliated). Replanting corn yielded 22 to 92 % more than the other treatments at the 100 % defoliated site, but decreased yield by nearly 30 % at the 55 % defoliated site. Clipping corn did not affect yields at the 55 % defoliated site, but reduced yield 37 % at the 100 % defoliated site. Clipping corn plants after frost proved an unreliable method of promoting recovery from early-season frost. Our field-by-field estimates of final corn stand potential on 4 June were fairly accurate. These assessments must be made to choose between replanting or leaving the plants alone