EFFECT OF SOLARIZATION AND COVER CROPPING ON PESTS, BENEFICIALS AND PEPPER YIELD

Authors: WANG, K-W - UNIVERSITY OF FLORIDA; MCSORLEY, R. - UNIVERSITY OF FLORIDA; SAHA, S - University Of Florida; Burelle, Nancy

Submitted to: Proceedings of Methyl Bromide Alternatives Conference
Publication Type: Proceedings
Publication Acceptance Date: 9/1/2006
Publication Date: 10/1/2006
Citation: Wang, K., Mcsorley, R., Saha, S.K., Burelle, N.K. 2006. EFFECT OF SOLARIZATION AND COVER CROPPING ON PESTS, BENEFICIALS AND PEPPER YIELD. Proceedings of Methyl Bromide Alternatives Conference. 21:1-4.

Interpretive Summary: Management practices that maintain soil health are becoming increasingly importatnt as non-chemical alternatives to methyl bromide. Objectives of this research were to examine effects of non-chemical pest management strategies on several key soil-borne pests and beneficial soil organisms using nematode communities as bioindicators, and to compare these treatments with methyl bromide fumigation. A field experiment was conducted in 2003 and 2004. Soil treatments implemented in summer included methyl bromide (MB) fumigation, solarization on raised bed (SB) and flat bed (SF) for 6 weeks, cowpea (Vigna unguiculata) cover cropping for 3 months (CP), combination of raised bed solarization and cowpea cover cropping (SCP), and a weed fallow throughout the summer as a control (C). At termination of summer treatment, all treated plots were planted to pepper (Capsicum annuum) under metalized mulch with drip irrigation. In both years, cowpea or solarization treatments alone were not as effective as methyl bromide for root-knot nematode suppression at the end of the pepper crop. However, the combination of solarization and cowpea matched the root-knot nematode suppression of methyl bromide, and suppressed populations of root-knot nematodes compared to the control. All solarization treatments were effective in suppressing weeds compared to the weed fallow control. Solarization outperformed methyl bromide for weed suppression in 2003 when weeds were not managed during the summer prior to the methyl bromide treatment. In 2004, when weeds in MB and C were managed by glyphosate and tillage in the summer, there were no differences among treatments in weed densities before and after a fall crop of pepper. Among the solarization treatments, SF did not suppress total weeds as effectively as SCP in 2003, probably because SF was installed manually and not sealed as tightly as SB and SCP, which were installed mechanically. Thus, heat was not trapped as efficiently in the SF treatment. Pepper yield was higher in two of the solarization treatments (SB and SCP) compared to MB and C in 2003. However, there were no differences among SF, CP, C and MB. Poor yield in MB in 2003 was probably due to poor weed management, resulting in cutworm damage on pepper seedlings early in the season. Thick weed residues in MB in 2003 likely interfered with the efficacy of MB. Although, weeds were managed properly during the summer in 2004, two hurricanes after pepper transplanting resulted in a Pythium epidemic. Consequently, crop yields were not different regardless of the summer treatments, despite differences in root-knot nematode numbers. Initially, mortality of pepper seedlings after the first hurricane was greatest in both of the cowpea cover crop treatments. However, after the second hurricane, plants in the methyl bromide treatment had twice the mortality as those in the flat solarization treatment. The extra organic matter in the CP treatment probably favored the development of Pythium, and MB fumigation had created a biological vacuum for the invading pathogens. In conclusion, a cowpea cover crop reduced the disturbance on nematode communities that contained beneficial nematodes involved in nutrient cycling but failed to reduce the population densities of root-knot nematodes at pepper harvest. However, combining CP and SB reduced the impact from SB alone on nematode communities, achieved a suppression of root-knot nematodes equivalent to MB at crop harvest in both years, suppressed weed population densities in both years, and had higher yields than MB in pepper in one year. Further research is needed to improve the SCP treatment for managing post-plant soil pathogens.

Technical Abstract: Management practices that maintain soil health are becoming increasingly importatnt as non-chemical alternatives to methyl bromide. Objectives of this research were to examine effects of non-chemical pest management strategies on several key soil-borne pests and beneficial soil organisms using nematode communities as bioindicators, and to compare these treatments with methyl bromide fumigation. A field experiment was conducted in 2003 and 2004. Soil treatments implemented in summer included methyl bromide (MB) fumigation, solarization on raised bed (SB) and flat bed (SF) for 6 weeks, cowpea (Vigna unguiculata) cover cropping for 3 months (CP), combination of raised bed solarization and cowpea cover cropping (SCP), and a weed fallow throughout the summer as a control (C). At termination of summer treatment, all treated plots were planted to pepper (Capsicum annuum) under metalized mulch with drip irrigation. In both years, cowpea or solarization treatments alone were not as effective as methyl bromide for root-knot nematode suppression at the end of the pepper crop. However, the combination of solarization and cowpea matched the root-knot nematode suppression of methyl bromide, and suppressed populations of root-knot nematodes compared to the control. All solarization treatments were effective in suppressing weeds compared to the weed fallow control. Solarization outperformed methyl bromide for weed suppression in 2003 when weeds were not managed during the summer prior to the methyl bromide treatment. In 2004, when weeds in MB and C were managed by glyphosate and tillage in the summer, there were no differences among treatments in weed densities before and after a fall crop of pepper. Among the solarization treatments, SF did not suppress total weeds as effectively as SCP in 2003, probably because SF was installed manually and not sealed as tightly as SB and SCP, which were installed mechanically. Thus, heat was not trapped as efficiently in the SF treatment. Pepper yield was higher in two of the solarization treatments (SB and SCP) compared to MB and C in 2003. However, there were no differences among SF, CP, C and MB. Poor yield in MB in 2003 was probably due to poor weed management, resulting in cutworm damage on pepper seedlings early in the season. Thick weed residues in MB in 2003 likely interfered with the efficacy of MB. Although, weeds were managed properly during the summer in 2004, two hurricanes after pepper transplanting resulted in a Pythium epidemic. Consequently, crop yields were not different regardless of the summer treatments, despite differences in root-knot nematode numbers. Initially, mortality of pepper seedlings after the first hurricane was greatest in both of the cowpea cover crop treatments. However, after the second hurricane, plants in the methyl bromide treatment had twice the mortality as those in the flat solarization treatment. The extra organic matter in the CP treatment probably favored the development of Pythium, and MB fumigation had created a biological vacuum for the invading pathogens. In conclusion, a cowpea cover crop reduced the disturbance on nematode communities that contained beneficial nematodes involved in nutrient cycling but failed to reduce the population densities of root-knot nematodes at pepper harvest. However, combining CP and SB reduced the impact from SB alone on nematode communities, achieved a suppression of root-knot nematodes equivalent to MB at crop harvest in both years, suppressed weed population densities in both years, and had higher yields than MB in pepper in one year. Further research is needed to improve the SCP treatment for managing post-plant soil pathogens.