Select the Crop emergence date (50% emergence) and set the upper limit to 330 or 500 e.g. if Max P-day is 379 then set the upper limit to 330. Initial spray is recommended in all cultivars at a value of 330 from Crop emergence. As the crop becomes more susceptible the dosage can be increased. In Denmark, we see the very susceptible stage at 500 P-days for late maturing varieties (e.g. Kuras)
Based on the age or developmental stage of the potato crop, the crop may be resistant, moderately susceptible or very susceptible (Abuley and Nielsen, 2017). The potato crop is resistant from crop emer-gence until tuber initiation or when the crop is 330 P-days old (Abuley and Nielsen, 2017). From tuber initiation or 330 P-days, the crop becomes moderately susceptible to early blight and thus indicates the time when fungicide spraying should be started. The age at which potatoes become very susceptible var-ies with the maturity period of the potato crop. Early maturing varieties reach the very susceptible stage earlier than late maturing varieties. In Denmark, we see the very susceptible stage at 500 P-days for late maturing varieties (e.g. Kuras).