Resistance Isn’t Always Futile

It’s raining outside my window here in Northeast Ohio as I write this. And that’s definitely been a rare site lately. Once-beautiful lawns have turned brown, and the sprinklers have been out to keep flowers and gardens from drying up. The forecast over the next few days looks promising, but we’ll have to wait and see.

When there’s a drought, it may be easy to take disease pressure for granted. And yet, that has not been the case this year. Downy mildew, in particular, has been a thorn in the side of many growers. In fact, some growers of cucurbits, which can include melons, cucumbers, pumpkins, and squash, are continuing to report downy mildew in their fields.

Controlling downy mildew and other diseases shouldn’t be too big of an issue. After all, there are a handful of fungicides on the market that are labeled for mildew control. In addition, many of the newer cucurbit varieties have been bred with resistance to downy mildew infection.

So what’s the problem? It’s resistance of another kind that is giving growers headaches.

Taking Action

Many of the newer chemistries on the market have specific modes of action pertaining to site and fungal growth and development. Combine this with the fact that some materials have different active ingredients, but similar or identical modes of action, and it creates a dilemma for growers.

“Fungicides with similar modes of action have the same affect on fungal growth and development, and overuse of high-risk fungicides with similar modes of action may lead to fungicide resistance development. One of the best ways to combat this problem is to alternate fungicide products with different modes of action.”

The previous statement might sound familiar, and that’s because it first appeared in American Vegetable Grower’s April 2007 issue, in an article titled, “Support Groups.” The article outlined the efforts of the Fungicide Resistance Action Committee (FRAC), a collective of industry personnel working together to address fungicide resistance management.

In recent months, FRAC has made a strong effort to target specific diseases, with downy mildew and powdery mildew among them (see the Web Extra icon below). They recognize that these pathogens can cause major problems if left unchecked, and if the materials used to control them no longer work, the problems escalate.

You should be just as concerned. Growers often cite input costs as one of the larger expenses they incur in running a farming operation. Hence, you want to make sure you’re getting the best use out of the crop protection materials you rely on.

Go to FRAC’s Web site, and you’ll find lots of helpful information on how to monitor resistance and rotate applications to prevent the potential for resistance. The Web site also provides updates on monitoring for specific diseases.

It’s important to do your homework on this issue. Don’t let these diseases become a headache for you.