Long Time Effect of Soil Solarization Integrated with Dazomet or Chicken Manure on Yield, Weeds and Root-Knot Nematodes in Tomato and Melon

Effects of 5-week soil solarization, either alone or combined with dazomet or a chicken manure compost, on tomato and melon yield, root-knot nematode infestation and weeds were investigated along three crop cycles in a plastic greenhouse infested by Meloidogyne javanica in Southern Italy. Solarization treatment, either alone and combined with dazomet or organic amendment, always resulted in a significant increase of marketable crop yield, and its effect lasted up to two years from the treatment. Nematode population indices and number of root galls were always lower in solarized soil than in untreated control. Organic amendment alone suppressed soil nematode population only in the first two crop cycles, though less than solarization and with no significant reduction of gall formation. Dazomet alone resulted in a yield increase only in the first tomato crop, with no significant reduction of soil nematode density and root galls. Solarization treatment completely suppressed the emergence of all the annual and perennial weed species, though C. rotundus was controlled only immediately after the treatment. Suppressivity of SOL on annual weeds and the perennial C. dactylon was extended to the tomato and melon crop following the treatment, but persisted on D. sanguinalis and P. oleracea, also in the third crop. Combination of solarization with dazomet or chicken manure compost did not enhance the suppressive effect on weeds. Solarization confirmed to provide an effective suppression of root-knot nematodes and weeds in the greenhouse vegetable crop systems of warm climate regions, with no need to be combined with other control tools.