ALFALFA DISEASE IN SOME ALBERTA SOILS

Abstract

Attempts were made to evaluate the potential biological factor causing poor growth (stunting) of alfalfa (Medicago sativa L.) on some soils in Central Alberta. Paratylenchus projectus which associates with stunted alfalfa was extracted from an affected soil. Alfalfa seedlings grown in sterilized sand culture assemblies were inoculated with P. projectus alone and in combination with dilutions from sterilized and non-sterilized affected and normal soils. Other studies included the effects of various sterilized and non-sterilized soil dilutions from an affected soil on plant growth and incidence of alfalfa stunting symptoms. Results indicate that P. projectus is not the biological factor causing alfalfa stunting. Typical stunting symptoms were observed on plants receiving non-sterilized soil dilutions from an affected soil, and the consistency of development of irregular reddish-brown root lesions on stunted plant roots confirmed the presence of other biological factor(s) causing the disease. It was reasonably well established that the root rot disease was caused by a microorganism(s). Further studies regarding root lesioning, isolation and identification of the microorganisms are being carried on in this laboratory.