We are collecting low to moderate numbers of aphids, both colonizing and non-colonizing, in our water pan and sticky card traps, with some pockets of high activity in both Aroostook and Central Maine. Black bean, Buckthorn, Foxglove and Potato aphids are the predominant species being collected, with some areas of high Buckthorn being found in Central Maine. Low numbers of Potato aphids and Green peach aphids have been found on potato plants within some fields.
We strongly urge all growers to be carefully monitoring aphid populations at this time. Growers should be aware that field scouting will not reveal the presence of non-colonizing aphids.
Colonizing Aphid Recommended Economic Thresholds
- Seed: 10% of plants with aphids, or 1 winged Green peach aphid
- Processing/Tablestock: 50% of plants with aphids, or 1 winged Green peach aphid
Colorado Potato Beetle
Colorado potato beetles are active in all areas. Adult beetles and larvae are being found throughout our scouting range.
CPB Recommended Economic Thresholds
- 25 Adults per 50 plants
- 75 Large Larvae per 50 plants
- 200 Small Larvae per 50 plants
European Corn Borer
Currently we have accumulated 956 modified growing degree days as of July 21, 2022. We expected the peak moth flight to occur between 700 and 900 modified growing degree days. Typically, peak egg laying will correspond to peak moth flight. At this point it appears that peak moth flight may have come and gone with only a minimal activity being detected this year as the most moths collected from any single trap in a seven day period was only five moths. There may be pockets of elevated activity within the growing area, however, we have not detected any significant activity at this point in time.
ECB Recommended Economic Thresholds
- 60 moths in a 7-day period in a heliothis-style trap
- 120 moths in a 7-day period in a black light-style trap
- 1 egg mass per 15 plants surveyed
Some potato flea beetle activity is being reported in Aroostook county and Central Maine. All growers will want to be monitoring for flea beetle activity. An average of 15 “shot” holes per terminal leaflet is the recommended economic threshold level for potato flea beetle damage.
Flea Beetle Recommended Economic Thresholds
- Average 15 “shot” holes per terminal leaflet
Low to moderate numbers of potato leafhoppers are being found on our sticky card traps and infield in both Aroostook and Central Maine. Potato leafhoppers are also being found on apples in Central Maine. Some Hopper burn is being reported in potato fields throughout the state. Growers will want to be scouting for leafhoppers, especially following storm fronts passing through the area.
Potato Leafhopper Recommended Economic Thresholds
- 10 nymphs per 100 leaves surveyed