Aphid populations are continuing to increase.  Many of our water pan traps throughout our trapping range are collecting low to moderate numbers of both buckthorn and potato aphids.  One water pan trap in Southern Aroostook yielded 28 potato aphids this week.  The principle species being found throughout our range in traps and fields is potato.  One field this week reported 5% of the plants with potato aphids, and colonization was beginning.  One winged Green Peach aphid was collected in a pan trap this week  in  southern Aroostook as well.  With the increased aphid activity that we are noting, seed growers may want to consider protecting potato plants at this time, even if a systemic material was used at time of planting.

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

- July 23, 2010

The beetle population in many fields is shifting from small-sized larvae to large-sized larvae with a mix of adults and small larvae.  At this point in the season, we are seeing beetle activity in some fields that were treated at time of planting with a systemic.  Several fields treated at time of planting have exceeded threshold levels for CPB this week.  Please remember that, in general terms, we expect approximately 60 days of control with seed or infurrow applied materials.  Many of our potatoes have been in for over 60 days, so seeing beetles within treated fields at this time is not unexpected.  If you are going to apply a follow up material, please do not use a Group 4A neonicotinoid, for resistance management purposes.

Recommended Economic Threshold

Adults: 25/50 plants surveyed

Large Larvae: 75/50 plants surveyed

Small Larvae: 200/50 plants surveyed

- July 23, 2010

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The potato late blight finds in southern coastal Maine have been on both tomato and potatoes.  Conditions have been conducive for the disease in these areas.  Please remember that warmer temperatures that we have been experiencing do not seem to shut the “newer” strains of late blight down as what happened with the “old” US #1 strain of late blight.  With the recent rain, all areas are reporting a 5-day protective spray.  Growers with fields located in high risk areas should consider the addition of a translaminar material as part of their regular protective program at this time. 

Trace levels of early blight are being found within some locations, predictive software indicates that early blight has the potential to become an issue this year. Growers with sensitive varieties may with to include an early blight control material this coming week.

- July 23, 2010

All trap counts are down significantly at this time.  Our scouts are finding some entry sites within a few fields.  Please remember that it will take significant numbers to create an economic impact.  If  you are finding a significant number of ECB entry sites, it has been reported that the chemical Rynaxypyr has some activity against ECB larvae which have entered the stalk. Corn borers have also been noted in oat stalks.

- July 23, 2010

Potato flea beetles have been found in the central Aroostook area.  Many times these insects will have an "edge effect" as they move into a field.  The economic threshold for potato flea beetles is when the terminal leaflets have an average of 15 shot holes.  Many times potato flea beetles can be controlled by spot spraying.  Neonicotinoid materials applied at time of planting should control these early potato flea beetles.

Redheaded flea beetle activity is being noted.

- July 23, 2010

Potato leafhopper activity is being reported in southern Maine. Leafhoppers have also been found on beans in the central Maine area. Trace potato leafhopper activity is being noted in southern and central Aroostook. Nymphs tend to cause more damage than adult potato leafhoppers. Potato leafhoppers will appear as neon green and will move sideways with a crab-like movement. Growers are encouraged to scout for leafhoppers. Please be aware that the potato leafhopper is one of the first insects that some neonicotinoids lose control of.

- July 23, 2010