8 December 1995

Improving leaf spot control

FEWER but more effective fungicide sprays to prevent dark leaf spot in brussels sprouts are likely thanks to a new computer model being developed by Horticulture Research International.

Humidity, temperature, rainfall and leaf wetness figures are downloaded twice weekly from field instruments to the office computer. This calculates optimum spray dates, reducing the need for unnecessary and costly routine spraying, says the HRIs Julian Davies.

Trials this year halved the number of applications but maintained crop quality, he explains. If repeated commercially, that could save £100-£150/ha (£40-£60/acre) in chemical cost. Limited grower trials will be conducted next year, with full release likely in 1997. Models for ringspot and white blister are being developed.