Winter 2014

As winter weather brings cooler temperatures, snowfall, and rains, mummies (or sclerotia) sit on the blueberry orchard floor accumulating degree days.

Rainfall and cooler temperatures are factors that influence the overwintering of M. vaccinii-corymbosi

As of November 2013, mummies in the field were already beginning to break dormancy and germinate.

Stipe initials are forming on overwintering mummy (sclerotium).

During December 2013, there were noticeably higher levels of germination and stipe initials were beginning to lengthen.

The blue arrows are pointing to a structure called a “stipe”. The stipe is the support for what will become an “apothecium” or fungal fruiting body, much like a mushroom cap. This picture is of a nearly-mature stipe and apothecium. However, in late-fall/early-winter, the beginning stages of stipe formation are visible on overwintering mummies in the field.

Most of the mummies found in the blueberry orchard can be found nestled under the leaf litter where they are less likely to dry out during periods of low rainfall.

The mummies generally fall from the bush in late-summer then are subsequently covered by fallen blueberry leaves.

Two rounds of mulching have now been applied to the experimental plots. Round One went out in late September when mummies still had their purple blueberry skin attached.

Round Two went out in mid-October after mummies had shed their purple blueberry skin.

It is unclear what function this removal of blueberry skin may have on the overwintering of the fungus, so it will be exciting to see if there are any differences in disease control efficacy.

In late-summer, mummies (sclerotia) still have purple/pink blueberry skin attached to the outer surface.

By early-fall, the blueberry skin is sloughed off, revealing dark colored mummies (sclerotia).

Round Three mulch is projected for mid-January. Pictures will follow.