Suppression of the emergence of wheat and barley by mancozeb

Abstract

Field studies were made to determine whether the seed dressing mancozeb 75 per cent was responsible for the poor emergence of wheat and barley observed in 1974. Four experiments were conducted, and, in two of these, wheat seed from batches that had produced poor commercial stands after treatment with the fungicide was used. The effect of the fungicides MBC 50 per cent, carboxin 75 per cent, thiabendazole 40 per cent, benomyl 10 per cent and fenaminosulf 7.5 per cent was also compared with mancozeb. Mancozeb reduced emergence of wheat and barley even when seed was sown in the season it was treated. When its effect on establishment of eight cultivars of wheat was compared with the other fungicides it reduced emergence to the greatest extent. Laboratory studies designed to elucidate the cause of reduced emergence in the presence of mancozeb 75 per cent established that it reduced both germination and coleoptile length. The studies suggested that reduced emergence in the field was due to the first leaf splitting the coleoptile prematurely.