Mid‐Season Stalk Breakage in Corn: Hybrid and Environmental Factors

Mid‐season corn (Zea mays L.) stalk breakage in south central Nebraska resulted from 100 mph winds on 8 July 1993 and 80 mph winds on 1 July 1994. Corn growth stages at the time of damage ranged from V10 to V14. Observations of field studies were taken to determine: (i) the impact of stalk breakage on grain yields of different hybrids; (ii) yield compensation by remaining plants; and (iii) the influence of soil and cultural factors on susceptibility to wind damage. We recorded stalk breakage on over 100 corn hybrids in evaluation trials at one site in 1993 and at two sites in 1994 to address objective i. Twelve hybrids were chosen at each site and yield components from broken and standing plants were recorded separately to determine whether remaining standing plants compensated for broken plants (objective ii). We also evaluated stalk breakage on a N management study and a site‐specific management/ variable rate study to address objective iii. In 1993 stalk breakage ranged from 7 to 88%, and grain yield was reduced 1.5 bu/acre for every 1% increase in stalk breakage. Breakage in 1994 ranged from 1 to 37% at one site and from 5 to 51% at the other site. Grain yield was reduced by 1.5 and 1.8 bu/acre for every 1% increase in stalk breakage, respectively. Remaining plants did not compensate for grain loss from broken plants at any site. Percentage yield loss is directly related to percentage stalk breakage. Stalk breakage increased with increasing N rate but was reduced with sidedress relative to preplant N application and no‐till relative to conventional tillage. Stalk breakage in the site‐specific management study correlated (positively) with soil organic matter content. Factors that accelerated plant growth early in the growing season increased susceptibility to stalk breakage. Unfortunately, management practices that result in slow early plant growth also limit yield potential. Planting tolerant hybrids is the best way to avoid losses. More information is needed on why individual plants break and why specific hybrids are more prone than others to mid‐season stalk breakage. Research Question Mid‐season corn stalk breakage occurred in south central Nebraska as a result of winds up to 100 mph on 8 July 1993 and up to 80 mph and on 1 July 1994. Growth stages of the plants ranged from V10 to V14. Although similar stalk breakage has occurred before in Nebraska, these events have been relatively minor. Subsequent to these events, stalk breakage occurred in south central Nebraska in 1996 and 1997, as well as in other years in Ohio, Minnesota, Montana, Iowa, and Illinois. The widespread area of damage in Nebraska in 1993 and 1994 provided a unique opportunity to evaluate factors influencing susceptibility to wind in existing studies. These data were collected to evaluate: (i) the impact of stalk breakage on grain yields for different hybrids; (ii) the relationship between yield loss and stalk breakage; and (iii) the influence of soil and cultural factors on susceptibility to wind damage. Literature Summary Mid‐season stalk breakage is a type of stem lodging also referred to as green‐snap or brittle snap. This typically occurs a few nodes above the soil surface, at or below the primary ear node and, in contrast to other types of stem lodging, usually occurs when stalks are moist and turgid. Little information is published on the impact of mid‐season stalk breakage. Between V6 and V12, corn plants increase in height rapidly through elongation of internodes. By V12, the number of potential kernels and the number of rows per ear are determined. By V17, the number of kernels per row is determined. Kernel weight is determined after pollination. Thus, timing of a storm in relation to a hybrid's growth stage can greatly influence a hybrid's ability to compensate since the potential capacity of the various yield components is determined at different stages of growth. The storm damage we are reporting occurred mainly after rows per ear were determined. However, the breakage occurred early enough that compensation by standing plants could still occur by increased kernels per row and by increased seed weight. The effects of organic matter differences, and N application timing and amounts have not been reported as influencing a hybrid's ability to withstand strong winds. Study Descriptions We recorded stalk breakage on over 100 corn hybrids at one site in 1993 and at two sites in 1994. Twelve hybrids were chosen at each site and yield components from broken and standing plants were recorded separately to determine whether standing plants compensated for broken plants at each of the three sites. We also evaluated stalk breakage on a long‐term N study and a site‐specific N management study. Applied Questions Do hybrids differ in susceptibility? Yes. In 1993 stalk breakage ranged from 7% to 88%. Grain yield was reduced 1.5 bu/acre for every 1% increase in stalk breakage (Fig. ). Breakage in 1994 ranged from 1 to 37% at one site (1.5 bu/acre yield decrease per 1% breakage increase) and from 5 to 51% at another site (1.8 bu/acre decrease per 1% breakage increase). Producers should plant hybrids less susceptible to mid‐season stalk breakage. What yield loss occurs for every percentage increase in stalk breakage? The effect of stalk breakage on grain yield of different corn hybrids (SCREC, 1993). image Yield loss decreased 1% for every 1% increase in stalk breakage. Grain production of standing plants did not compensate for grain loss from broken plants at any site. Do soil and cultural factors affect susceptibility to wind damage? Yes. Stalk breakage increased with N rate but was reduced with sidedress N application and no‐till. Stalk breakage in the site‐specific management study showed a low but significant correlation with soil organic matter content. Factors that accelerated plant growth early in the growing season increased susceptibility to stalk breakage. What can farmers do to reduce the impact of destructive winds? Plant agronomically sound hybrids that are less susceptible to breakage. Many seed companies are aware of the breakage tolerance of their hybrids based on experimental and in‐field experience. Plant crops in addition to corn. Neither grain sorghum nor soybean were affected by the storms. Plant in different row orientations. The 1993 storm damage was worse in north‐south rows; the 1994 damage was worse in east‐west rows. Plant wind breaks. According to James Brandie, University of Nebraska, Lincoln, wind speeds within corn canopies sheltered by wind breaks near Lincoln, NE, in 1993 were generally less than 20 mph with no stalk breakage while, in exposed areas, wind speeds exceeded 40 mph and stalk breakage was considerable.