Wh. Elmer et Fj. Ferrandino, COMPARISON OF AMMONIUM-SULFATE AND CALCIUM NITRATE FERTILIZATION EFFECTS OF VERTICILLIUM WILT OF EGGPLANT, Plant disease, 78(8), 1994, pp. 811-816
Eggplants fertilized with either (NH4)2SO4 or Ca(NO3)2 were grown over
three seasons in soil with high, low, or no inoculum of Verticillium
dahliae. Early in the season before the onset of symptoms, eggplants t
reated with (NH4)2SO4 had more nonstructual carbohydrates in the roots
and leaves than plants treated with Ca(NO3)2, and the rhizosphere was
more acidic. Densities of total rhizobacteria and fluorescent pseudom
onads were not affected by nitrogen fertilizers. After anthesis when s
ymptoms appeared, the fertilizer treatments did not affect the percent
age of diseased foliage or the amount of root and stem colonization by
V. dahliae. However, fertilization with (NH4)2SO4 was associated with
increased leaf and root levels of N, P, and Mn, compared with fertili
zation with Ca(NO3)2. In soils with high inoculum density, there was n
o difference between the nitrogen fertilizers in effect on eggplant gr
owth or yield. In soils with low inoculum densities, however, plants f
ertilized with (NH4)2SO4 were significantly larger, had more large lea
ves and fewer small leaves, and had 33-44% more marketable yield than
plants fertilized with Ca(NO3)2. Fertilization with (NH4)2SO4 in soil
with low inoculum densities may be useful in the management of Vertici
llium wilt of eggplant.