Submitted to: Subtropical Plant Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/10/2009
Publication Date: 2/7/2010
Citation: Greenberg, S.M., Bradford, J.M., Adamczyk Jr, J.J., Smart, J.R., Liu, T. 2010. Insect population trends in different tillage systems of cotton in south Texas. Subtropical Plant Science. 62:1-17. Interpretive Summary: Annual diversity of harmful organisms brings a significant loss on cotton production. Chemical insecticides continue to be the main tool for insect control (average 7.3 kg/ha of active ingredient applied to protect cotton from harmful organisms annually). The use of different tillage practices is an important cultural tool. Tillage operations modify soil habitats where some insect pests and beneficial insects reside during at least part of their life cycles. These modifications can alter survival and development of both soil and foliage-inhabiting insects. Dryland cotton production in the LRGV is complicated by erratic precipitation, ranging from 40.6 to 55.9 cm annually that occurs primarily during the spring and early summer. Water availability for irrigation has become a major concern for south Texas. In this case, conservation tillage can be used for improving soil moisture status. We studied the effects of conservation and conventional tillage systems in dryland and irrigated cotton on soil surface temperatures, soil moisture, plant canopy structure, light interception, timing of fruit set, and how these factors affect boll weevil, and some secondary insects (complex lepidopterans, whitefly, thrips, fleahoppers, complex predators) populations and damage throughout the growing season. These findings will make utilization of different tillage systems for management of harmful and beneficial organisms in cotton more practical. Such control will reduce the need for additional insecticides use and associated environmental problems. Conservation tillage reduces soil erosion, conserves soil moisture, and substantially lowers cost of field operations compared to conventionally tilled systems.
Technical Abstract: This study was conducted during 2000 – 2006 in experimental plots of the USDA-ARS-Subtropical Agricultural Research Center in Weslaco, Texas and privately owned cotton fields near Hargill and Santa Rosa, Texas. We evaluated the effects of conservation and conventional tillage systems in dryland and irrigated cotton on abiotic and biotic factors and how they affect main insect populations and damage throughout the cotton growing season. Cotton producers are incorporating significant changes in management systems in an effort to decrease production costs and improve profits. For this reason, conservation tillage practices have been adopted across most of the cotton acreage in the southern United States. This manuscript discusses changes in the pest spectrum and severity of pest problems associated with conservation versus conventional tillage systems in both irrigated and non-irrigated cottons. Our results demonstrated that different tillage practices had indirect potentially positive or negative effects on pest and beneficial populations in cotton and other crops. The direct effects of insect pest populations could develop through abiotic and biotic factors which can be created or corrected by conventional or conservation tillage systems.