ANALYSIS OF CROP LOSSES IN TOMATO DUE TO PRATYLENCHUS-PENETRANS

Abstract

The effects of P. penetrans upon yields of ''Veebrite'' tomato [Lycopersicon esculentum] were studied at initial soil population densities (Pi) of 360, 2010, 4580 and 14,360 nematodes/kg of soil in 20 cm (i.d. [inside diameter] clay-tile microplots. The lowest Pi stimulate fruit production. Higher Pi suppressed fruit production (total wt of marketable tomatoes and numbers of intermediate- and large-sized fruits), in comparison to control yields, the highest Pi resulted in 38% fewer fruits which weighed 44% less. These losses were at least partly due to a delay in fruit ripening, caused by the nematodes, which did not become apparent until the 4th wk. Nematode populations in the soil increased at all but the highest Pi; final populations were around 7000/kg of soil. Nematode populations in roots ranged 230-590/gm of root at the completion of the experiment. Nematode control by fumigation would definitely be warranted at soil population densities of 2,000/kg or higher; with 500-200/kg, the decision to fumigate would depend on soil type and economic and biological factors.