Plum curculio early season monitoring and phenology

Fruit growers can better control plum curculio with early season monitoring and understanding the phenology of this pest.

Plum curculio early season monitoring

Plum curculio over-winter as adults in the soil, litter, ground cover trash in orchards and surrounding areas. As soon as daytime and evening temperatures exceed 60 degrees Fahrenheit, plum curculio will begin to move especially when a light, misty rain or humid nights co-occur with early spring warming trends. The weevils move into orchards and begin to feed as leaves begin to emerge. Their feeding activity expands to blossoms, stems and fruit as they become available.

Traps are a good indicator of likely plum curculio pressure in the area and should be placed on the borders of orchards where producers or scouts have observed damage in past years. Often these locations have woods, unsprayed orchards, feral trees or other sources of overwintering plum curculio populations.

Population pressure rating: general trap catch per week bloom to 370 DD50 plum curculio

Rating

Apple

Cherry

Peach

Pyramid

Screen

Pyramid

Screen

Pyramid

Screen

V. Low

1

0

0

0

1

0

Low

2-3

1

1

0

2-3

1

Mod

4-7

2-3

2

1

4-7

2-3

High

8-11

>4

3-4

2

8-11

3-4

Extreme

>12

>4

>5

>3

>12

>4

 Plum curculio phenology

The Pesticide Alternatives Lab at MSU has been working to improve capabilities for predicting life stages for a better understanding of when egglaying occurs and when larval instars are present. At 275 DD50 F from March 1, all female plum curculios should have at least one mature oocyte (egg). It can be expected that 340 DD50 F after petal fall (if petal fall =500, then 500 + 340 = 840 DD50 F), 40 percent of the cumulative oviposition cycle is completed in apples in New York. Larvae from this overwintering brood will exit fruit into the soil, where they will pupate and emerge as summer generation adults.

Plum curculio graph

Degree days accumulated as of 5.9.2013. Degree day data obtained from Enviro-weather

Site

Accumulated degree days (base 50 F)

Site

Accumulated degree days (base 50 F)

Bear Lake

167.9

Fennville

197.6

Benton Harbor

214.6

Hart

157.5

Benzonia

155.8 

Hartford

220.8

Berrien Springs

218.5

Lapeer

198.2

Clarksville

186.5

Ludington

147.2

East Lansing

202.9

Northport

112.3

Eastport

145.5

NW Station

153.2

Elk Rapids

143.1

Sandusky

171.8

Emmett

179.1

Sparta

196.6

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