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Local and Systemic Control of Phytophthora infestans in Tomato Plants by dl-3-Amino-n-Butanoic Acids. Yigal Cohen, Professor, Department of Life Sciences, Bar-Ilan University, Ramat-Gan 52900, Israel. Phytopathology 84:55-59. Accepted for publication 30 September 1993. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/Phyto-84-55.

Tomato plants (six- to seven-leaf stage) sprayed with the nonprotein amino acid dl-3-amino-n-butanoic acid (dl-?-amino-n-butanoic acid) were protected against a challenge infection with Phytophthora infestans. A single foliar spray (19.4 mM, 2,000 ppm) applied either before or after inoculation provided more than 95% control of the disease compared with unsprayed challenged plants. The concentration of the racemate required to achieve 50% control of the disease was 175 ppm (1.7 mM). dl-2-Amino-n-butanoic acid was half as effective compared with the dl-3-amino-n-butanoic acid, whereas the 4-amino-n-butanoic acid was ineffective against the blight. dl-3-Amino-n-butanoic acid protected against seven isolates of P. infestans in seven cultivars of tomato, which carry various levels of susceptibility to the blight pathogen. It produced minor phytotoxic symptoms in tomato leaves. It had no effect on sporangial germination in water or on leaf surfaces of tomato nor on mycelial growth in rye seed liquid medium.

Additional keywords: aminobutyrates, induced resistance, late blight, Lycopersicon esculentum, plant defense.