Captan is a fungicide with protective and curative action. Many of the general purpose product mixes contain captan (see Table 2.4). Captan is effective against scab, black rot, white rot, bitter rot, Brooks spot, and blossom end rot on apples. It is effective against sooty blotch and flyspeck if the last spray application is not more than 30 to 40 days before harvest. It is not effective against the rusts, fire blight, or powdery mildew.
Where the early season apple scab control program fails and scab becomes established in the trees, captan at low rates cannot be expected to provide control. This fungicide is highly effective, however, in reducing spore germination. Use at least 4 to 5 T per 2.5 gal applied at intervals of no more than 10 to 14 days.
On stone fruits, captan is a good fungicide for the control of brown rot and scab when adequate spray schedules are followed. Captan plus wettable sulfur can be used on peaches when brown rot, scab, and mildew are present. Captan is effective against cherry leaf spot and brown rot on tart cherries if the diseases are at a low level and the spray intervals do not exceed 2 weeks.
Captan has caused a necrotic spotting, yellowing, and dropping of leaves when used under poor drying conditions or in combination with sulfur, especially on Delicious, Stayman, Baldwin, and King apple varieties. Foliage of d'Anjou pears has been stunted and cupped. Necrotic spots on fruit and foliage have occurred on both plums and prunes where captan was used from petal fall until the fruit begins to ripen. Its use usually results in acceptable fruit finish on apples, peaches, and nectarines. Captan residues on peaches at harvest may cause increased skin discoloration from abrasions that occur during picking and packing. The leaves of some sweet cherry varieties may be injured by repeated captan applications. A full-season program of captan may require the use of miticides or close adherence to a pest management program. Captan is not registered on pears.
Captan has few spray incompatibilities, but it should not be used with oil, lime, or other alkaline materials. Using captan within a week either before or after an oil application may result in leaf injury on apple trees. Combinations with sulfur might result in increased injury under high temperatures and high relative humidity. The preharvest interval for captan is 0 days. Please remember to check the label for rates and application times for best disease control.