SDHI fungicides for protecting fruit from brown rot infection

 

American brown rot is caused by the fungus Monilinia fructicola. This fast-growing fungus is an important pathogen on cherries (sweet cherries in particular), peaches, apricots, nectarines and plum. The fungus attacks fruit, blossoms, spurs and shoots; under ideal infection conditions, the fungus can rot individual cherry fruit within 24 hours (see photo). The fungus sporulates from infected fruit, continually increasing inoculum for further infections to other fruit on the tree. Under ideal conditions, sporulation can be initiated within three days after infection. American brown rot causes fruit rot before and after harvest, greatly reducing quality and quantity of the crop, particularly in heavily bunching sweet cherry varieties.

 

Factors that contribute to American brown rot infection before harvest include warm, wet conditions as the fruit begin to ripen and increase in sugar content. Although fruit injury may lead to increased infection, the American brown rot fungus can cause infections when no wounds are present. Other factors influencing increased infection are fruit-to-fruit or fruit-to-branch contact on trees.

 

It is not possible to stop brown rot infections on fruit once they are initiated; however, fungicide applications will protect other fruit that have not been infected. 

 

The two most important issues in American brown rot control of fruit infection are use of an effective fungicide and fungicide coverage of fruit surfaces.

 

Except SDHI fungicides, there are three main classes of fungicides with effectiveness against American brown rot: