Compatibility of Metalaxyl with Rhizobium Meliloti on Alfalfa Seed to Control Pythium Damping Off
- K. L. Edmisten ,
- D. D. Wolf and
- E. L. Stromberg
Metalaxyl [N-(2,6-dimethylphenyi)-N-(methoxyacetyl)-alanine methyl ester], an acylalanine fungicide, has been reported to be effective in controlling fungi in the order Peronosporales. Metalaxyl shows promise for control of Phytophthora root rot (Phytophthora megasperma Drechs.) and damping-off (Pythium spp.) in seedling alfalfa (Medicago satlva L.) if seed treatment does not interfere with the N2-fixing bacterium (Rhizobium meliloti Dangeard). Spring nofill plantings often are made earlier where fall-applied herbicide is used to suppress sod. Plantings made in cooler weather are more susceptible to seed- and soil-borne diseases. Compatibility of this fungicide with R. meliloti when used as a seed treatment was determined using the most-probable-number technique, by measuring seedling growth, total seedling crude protein, and N2 fixation as estimated by acetylene reduction. Metalaxyl had no detrimental effect on viability or N2-fixing capability of R. melilotl at recommended rates of application. Under growth chamber conditions, metalaxyl increased seedling survival by 45 to 60% over nontreated P. ultimum Trow infested controls.
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