Also, using Tilt as a protectant reduces the danger that the rust fungus may develop resistance to Tilt. Regardless of the fungicide used, it is important to apply early before rust populations are high. Once populations are high, control is very difficult. Chlorothalonil cannot be applied within 14 days of harvest, Tilt within 28 days and maneb within 30 days. Since it is not economic to apply after lower pods of pintos begin striping, these harvest restrictions are consistent with economic control practices.
Timely action is important.
If no rust has been found in an area, it is all right to wait until rust has been detected before spraying. However, if rust is present and becoming severe in the area, it is time to spray all susceptible fields in the area, even those in which rust has not been detected. Some fields in this area are showing very high incidences, but still relatively low severities. These fields may have additional development of scab, until hard dough stage is reached. Fields in some of these counties were already being swathed on July 21.