Acylalanines diseases

Within the past ten years, the market introduction of several new types of fungicides has significantly improved the prospects of controlling the Oomycetes. They belong to five different chemical classes the carbamates, the isoxazoles, the cyanoacetamide oximes, the etheyl phosphonates, and the acylalanines and related compounds. The chemical structures of those chemicals that have reached the commercial level are shown in Figures 3-5 (29, revised). Trade names, formulations and first reports are summarized in Table II (29, revised). The biological characteristics of these new fungicides and their impact on disease control have been reviewed by several authors (10, 16, 27, 28, 29, 33). 

Metalaxyl and most of its active analogues are chiral molecules. Chirality is caused by the asymmetric carbon atom in the alkyl side chain of the alanine moiety. The two optically pure enantiomers S (+) and R (-) differ widely in their biological activity both in vitro and in vivo. In all experiments, the R (-) enantiomer was more active than its antipode S (+) (22, 24, 30). The main characteristics of metalaxyl have been discussed in detail by several authors (J, 21, 28, 29, 32> 38). Of particular value is the rapid uptake of metalaxyl by the plant tissue, especially under the wet conditions that favor foliar Oomycete diseases. Acylalanines are easily translocated in the vascular system of the plant after foliar, stem or root treatment (35, 47). The predominant route of transport is the transpiration stream, thus apoplastic (12, 35). Symplastic transport occurs but is much less evident (35, 47). In potatoes treated by foliar sprays of metalaxyl concentrations (0.02-0.04 ppm), Bruin et al. (SO were able to demonstrate protection of harvested tubers from late blight. 

Metalaxyl or methyl-N-(methoxyacyl)-N-(2,6-xylyl)-DL-alaninate Acylalanine Inhibits protein synthesis in fungi, systemic with protective action Control of air- and soil-bome diseases on crops 11-29... 

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