Boll removal studies in cotton

PI(s): Herbert, Jr, David Ames, Malone, Sean

Investigators:

Abstract: In developing management strategies for hemipteran pests in cotton (Gossypium hirsutum L.), it is important to understand the potential of plants to compensate for loss of the fruiting structures. Because of its northern latitude, Virginia has fewer available heat units relative to other cotton-producing states. Therefore, there may be limited opportunity for compensation relative to more southerly production areas. Previous work in Virginia demonstrated that cotton can sustain relatively high levels of first position square loss with no yield loss. This study evaluated the impact of a single event loss of 10 to 14-d-old bolls via mechanical removal on cotton lint yields with the premise that boll loss would have greater impact than square loss as less time and fewer heat units are available for compensation. Field experiments examining four levels of boll removal (0, 5, 15, and 20%) were conducted in 2001, 2002 and 2003. Each boll removal level was imposed at three different dates, beginning 2 wks after first flower and at 3- to 5-day intervals thereafter. Yields ranged from 1103 to 1422 in 2001, 909 to 1124 in 2002, and 843 to 1015 kg lint per ha in 2003. There were no significant differences in lint yields among the boll removal dates or removal levels. The results of our study showed that cotton in Virginia, which approaches the northernmost latitude for cotton production, is capable of sustaining losses as high as 20% of 10 to 14-d-old bolls at a single removal event without affecting lint yield. Results were consistent despite the wide variation in rainfall and temperatures during the three study years.

Description:

Results of this study showed that cotton in Virginia can tolerate and compensate from some level of boll loss without suffering a reduction in lint yield. Currently, both Virginia and North Carolina Cooperative Extension information for management of hemipteran species in cotton recommends initial protective action at 10% internal injury to 10 to 14-d-old bolls. That 10% encompasses all types of damage, a lot of which may not have a large impact on final lint yield. The most important implication of this work is that the action threshold for hemipterans in Virginia may be increased to at least 15% without jeopardizing lint yields. This means that fewer fields may require protective insecticide sprays. These studies could also have implications for insects beyond plant bugs and stink bugs (i.e., heliothines) which also cause boll abscission and damage.

Commodities: Cotton

Resources: Agricultural Experiment Station Facilities

Disciplines: Integrated Pest Management

Audiences: Agribusiness, Commodity Groups, Extension Agents, Producers, Researchers