May 4, 2012
Scout and spray to control mummyberry

For blueberry growers, mummyberry can lead to frightening losses if not managed properly.

Mummyberry is a fungus that overwinters in the previous year’s berries that fell on the ground, according to Washington State University’s blueberry IPM website. When it starts to warm up and there is enough moisture, a small, mushroom-like spore cup emerges on the fallen berries. The mummyberry spores are released and spread by wind.

The “mummies” are the infected berries that fell to the ground, which look like tiny black pumpkins that are about three-eighths of an inch in diameter, said Annemiek Schilder, a plant pathologist with Michigan State University (MSU). They are often found partially embedded in the soil or underneath leaf litter. The spore cup grows out of them.

The mummyberry fungus survives in the “mummies” for at least two years. Once they have germinated, however, the fungus dies and no longer poses a threat of infection, Schilder said.

Scouting and spraying

Schilder suggests scouting in wet areas, and close to wooded areas near blueberry patches.

Clair Klock, owner of Klock Farms in Corbett, Ore., said he has had some success controlling mummyberry on his 27-acre farm.

“I use Indar and Pristine based on scouting of my field, as well as the duration of blossom set, temperature, wind and moisture,” he said. “I can get 99 percent control or better on only one or two sprays with the proper scouting and timing.”

The unseasonably hot spring had fruit plants off to a quick start in Michigan, said Mark Longstroth, a small fruit Extension educator with MSU. Blueberry flower and leaf buds are opening, so growers need to think about mummy berry protection, especially when it warms up and spring rains come.

When mummyberry attacks

Most of the fields are getting ready to, or are blooming, so it is too late to spray for shoot strike, Longstroth said. The season started hot and dry and in many fields there were only a few small trumpets because of the dry soil conditions. Growers should protect flowers if they find shoot strike in or near their fields. Good pollination weather is good mummy berry weather during bloom. The flower is most susceptible when it opens so growers should apply control at early bloom and at full bloom.

Mummyberry is a serious issue for Dave Beach, owner of Beach Family Farms in Sherwood, Ore. Beach grows highbush berries and tries to be pesticide-free. For about 25 years, he never had mummyberry problems on an otherwise healthy half-acre of u-pick berries.

“About four years ago, it showed its head a little,” Beach said. “The following season we got killed: about one-fourth of our usual crop.”

After that, Beach went to great effort to spread sawdust and spray with BUMPER. The next season showed great improvement, but Beach still saw plenty of mummyberry.

The next season, Beach tried a more organic approach by not mowing until after all blooms had dropped, combined with minimal spraying and no new sawdust.

“Our entire crop was wasted,” he said. “For the first time in our (then) 28/29-year history, we didn’t even open because of a mummyberry-destroyed crop.”

This year, Beach said he is back to spraying on an “often-as-can-get-into-field” schedule. It has been a very wet and rainy spring in Oregon.

“Only time will tell what it brings us in July,” Beach said.

By Derrek Sigler, Assistant Editor

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