Disease management of organic tomato under greenhouse conditions in the Jordan Valley

Abstract

Production of organic tomato under greenhouse conditions has significantly increased in the last few years. Although greenhouse systems provide the option of off-season production and expansion of markets over traditional outdoor field systems, such systems also pose unique challenges with regard to pest management. An experiment was conducted in the Jordan Valley during the fall of 2011/2012 to evaluate the effects of integrated pest management that combines different preventive and control measures, on diseases and pests of tomato grown under greenhouse conditions. The experiment consisted of three treatments (organic farming, conventional farming and integrated pest management (IPM) farming) with four replicates arranged in a randomized complete block design (RCBD). The plant diseases and pests were monitored in all treatments. Powdery mildew disease was recorded at 6 weeks after transplanting in all treatments and at 22 weeks after transplanting, the disease incidence was 74%, 68% and 57% in the IPM, conventional and organic treatments, respectively. However, the disease severity did not exceed 1.5 in any of the treatments. Early blight disease appeared at 16 weeks after transplanting and at 22 weeks after transplanting, the disease incidence was 62%, 54% and 47% in the IPM, conventional and organic treatments, respectively. Neither bacterial symptoms nor nematode symptoms were observed in any of the treatments. Enzyme-linked immunosorbent assay (ELISA) tests revealed the presence of Tomato ring spot virus (ToRSV) and Tomato bushy stunt virus (TBSV). Overall, the study showed that there were no significant differences between the three treatments with regard to tomato plant height, width, circumference, number of flowers/cluster, number of clusters/plant, fruit yield, shoot dry weight and root dry weight. Furthermore, several quality parameters of tomato fruits were studied; dry weight, lycopene content and pH were found to be significantly higher in the organic tomatoes.