Warm weather and a wet weekend put blueberries at risk for mummy berry

Warm weather has blueberries advancing rapidly. Warm rain will be ideal for mummy berry shoot strike infections. Growers need to protect newly emerged leaves against mummyberry shoot strikes.

The unseasonably hot spring has fruit plants off to a quick start. Blueberry flower and leaf buds are opening (Photo 1), so growers need to think about mummy berry protection. The hot weather is supposed to end today with the passage of a cold front that will bring cooler weather. Associated with this front is a good chance of rain from Thursday night (March 22) through Friday and Sunday. These rain events will have warm rains (50 to 60°F). This means that the infection period for mummy berry will be very short (see Table 1).

Bluecrop
Bluecrop in Berrien County and burst flower

buds, and the leaves are out.

Several people have reported to me that they have found just a few or that they are just starting to open. I scouted for mummy berry mushrooms yesterday and found them very hard to find. I think the hot, dry weather may have set them back. My guess is that we are just at the beginning of the spore release period and have probably been there for a day or two. So the risk is real. Under hot conditions, the trumpets do not last long (less than a week), but I would not be surprised if we get more mushrooms coming up after a rain. I do know that the weather has not held back the plants and I really feel growers need to apply fungicide to protect against shoot strikes.

Mummy berry trumpets
Mummy berry trumpets have just started to
open and release spores.

Table 1. Mummy berry shoot strike infection

Wetness

Temperature (ºF) During Wet Period

Duration (h)

36

43

50

57

65

2

0

0

0

0

0

4

0

0

0

0

0

6

0

Low

Low

High

High

8

0

Mod

High

High

High

10

Mod

High

High

High

High

15

Mod

High

High

High

High

24

High

High

High

High

High

Table source: Paul Hildebrand, Ag Canada, Nova Scotia.

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