Neck rot (Botrytis allii) of bulb onions

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Abstract
SUMMARY: The percentage of bulbs with neck rot in store was determined by the number of onion plants with Botrytis allii infected neck tissues in the field. Since infected plants were obtained mainly by sowing infected seeds, it was established that the seeds were main source of neck rot in stored bulbs.The disease failed to spread from infected bulbs to healthy bulbs in store but affected bulbs became progressively more rotten during storage.In 1972, dusting seeds with 1 g benomyl/kg reduced neck rot in the stored bulbs from 50 to 8%. However, there was some cross infection from the control plots to the plots raised from benomyl dusted seeds 1·5 m distant. In 1973 and 1974, all plots were placed 165 m or more from one another to reduce spread of the disease. Benomyl applied to seed samples containing 1, 10 and 20% infection reduced the average neck rot percentage in stored bulbs from 10·1 to 0·4% in 1973 and from 26·2 to 3·8 % in 1974. The amount of neck rot in store was directly related to the percentage infection of the onion seeds. However, the number of infected bulbs in store was proportionally greater in 1974 when weather conditions were more conducive to spread of the disease in the field.