Idaho
                         Aphid
                   Flyer

BIRD CHERRY OAT APHID

James B. Johnson, Juan M. Alvarez, & Monica A. Wiebe
August 10 , 2001                                                                                                                                                                                                                                         Vol. 16 No. 6

Fall Planting

    Bird cherry oat aphids have increased in most locations. The earlier than normal harvest, has thoughts running towards earlier than normal fall planting. This is especially true if we get some much-needed moisture. CAUTION! Aphid numbers are too high to predict a safe planting date without the use of a systemic insecticide. Remember-green bugs and bird cherry oat aphids are both insect vectors of barley yellow dwarf virus. Aphid numbers are also used as an indicator of wheat streak mosaic virus. Cereal crops with high resident populations of bird cherry oat aphids can be significantly damaged by BYDV. It is difficult to recommend an action threshold because the damage depends upon what percentage of the aphids are carrying the virus. This can vary greatly from year to year. Another complicating factor is the fact that symptoms of the disease are sometimes ambiguous and often do not show up until spring. As a rule, dry land wheat will suffer more than irrigated crops. Because of the many factors involved, treatment decisions should be made on a case-by-case basis.
   Russian wheat aphid numbers increased in most locations in the last 2 weeks. Growers in these areas should monitor fields that are still vulnerable to RWA damage.  

Russian Wheat Aphid Thresholds

Season

Plant growth stage

Threshold

Fall

Seedlings (l tiller)

10% plants infested

Fall

Larger plants

Treat if plants are stressed or there is danger of winter kill

a/   After the soft dough stage, insecticide treatment will have little to no benefit.

Green Peach Aphid
            After surveying several fields in the Aberdeen area last we noticed the decrease in Green Peach aphids. However, we still urge caution. Even with low vector numbers the risk of virus infection in the field remains high. This is most important to seed growers. Thus, growers should not stop scouting in the fields twice a week. Russet Burbank and seed growers close to Ranger or Shepody fields should be especially careful. Aphids will move to late potatoes when the early potato vines are killed and can still cause damage. Remember to check U of I recommendations for GPA/PLRV management.


  Funded by the University of Idaho Agricultural Experiment Stations and the Wheat & Barley Commissions.

 

IDAHO
APHID DATA

Samples collected July 27 & August 3, 2001 

Cereal

Others

Total

Suction Trap Location

Russian Wheat Aphid

Green Bug

Bird Cherry Oat Aphid

English Grain Aphid

Rose Grass Aphid

Corn Leaf Aphid

Apple Grain Aphid

Green Peach Aphid

Potato Aphid

Pea Aphid

Spotted Alfalfa Aphid

Bean Aphid

(All Aphids)

Moscow*


36

-


5


21


38

-

-


1

-


8

-

-

0
137

Lewiston

14
22

-

10
10

11
13

75
67


2

-

6

-

19
9

-

-

149
147

Parma

1
4

1
1

3
16

2
1

6
5


4

-


1

23
26

28
37

2
3

-

95
126

Picabo

-


1

1
2

-

92
30

-

-

1

-

6
2


2

-

111
44

Kimberly

11

-

7
18

-

2
4

2
1

-

1

-

12
2

2
1

-

45
35

Burley

44
21

7
14

37
42

-

23
19

1
3

-

-


3

2
3

1

-

148
136

Aberdeen

2
5

2
7

35
85


1

10
27

4
15

1
1

-

1
5

1
6


1

-

80
184

Rockland

27
18

1

13
13

-

3
5

1
2

-

-

-

-

-

-

46
43

Arbon

4

-

21

-

4

2

-

-

-

-

-

-

32
NS

Soda Springs

4
29


3

150
455

-

5
15

11
44

-

-

1

5
2

-

-

188
571

Ririe

3

1

993
121

-

62
10

22
6

2

1

-

-

5

-

1118
141

Tetonia

-

1

420
490

-

73
246

15
57

4
1

-


1

4
2

5
1

-

570
829

 Moscow trap problems 1st week