• Late blight update

• Corn pests

• Pepper maggot

• Pumpkins

• Cercospora leaf spot on beets and Swiss chard

Late blight update
We are now starting to see multiple farms per town with late blight in the middle and upper portions of the Connecticut River Valley in Hartford County, but we have also found it or confirmed reports from commercial farms in Fairfield, Lichfield, Tolland and New Haven Counties. Most of the counties in New York now have confirmed cases of late blight on commercial farms as well, including all those along the Connecticut border.  Homeowner plantings that were infected early are starting to go down, as are unsprayed organic plantings.  One grower said she lost her first planting of 1,500 plants in just 4 days and it is into her second planting in a separate field. I found late blight on potatoes on an organic farm up in Litchfield County early this week.  Cornell Extension reports that this strain of late blight seems to be much worse on tomatoes than on potatoes, although both crops are susceptible. I looked at one field of tomatoes yesterday that had been sprayed with our normal tomato fungicides every other day since the beginning of June (because it rained almost every day) and had the first systemic/protectant combo application 2 days ago.  Despite the tight spray schedule, most of the plants in the field showed some sign of late blight...either just a couple of leaf lesions or a combination of a couple of leaf lesions and stem lesions. Plum tomatoes seem to be holding it off better than round tomatoes so far.  I also got back to several farms that we found late blight on last week, that had used systemics/protectant sprays.  One farm that only had a couple of plants infected last week had removed the plants and applied Tanos + Bravo, and had no sign of late blight this week, but that was the exception rather than the rule.  Three other farms that had used either Tanos, Curzate or Previcur Flex for their systemic with Bravo, copper or Manzate, and may or may not have removed severely infected plants, the disease had definitely spread to some new plants.  The good news was that it was mostly limited to a couple of leaves and/or stem lesions and the plants were all still alive. So the new spray schedule of a systemic plus a protectant alternated with a different systemic/protectant the next week seems to at least be slowing the disease spread substantially.  I also found that their were a couple of leaf lesions on greenhouse tomatoes on one of those farms, so an application of Previcur Flex on your greenhouse tomatoes is definitely warranted.  I scouted tomatoes on some farms that did not have late blight last week and after applying the systemic and a protectant, they did not have any sign of the disease this week, so there is hope for those of you wondering about spending all this money on fungicides.  Some growers were unable to find Presidio, so I called Helena Chemical Co. in Hatfield, Ma.  They said they had 3 quarts left at $278 each, but were expecting another shipment by midweek next week.  If you are looking for more information about the spray options for late blight, please see last weeks pest message on our UConn IPM Web Site at www.hort.uconn.edu/ipm/.  Some of the best combinations for spraying both tomatoes and potatoes include Tanos (3 dh) + Bravo alternated with Previcur Flex (5dh) + Manzate.  Another alternative for tomatoes only is Presidio (2dh) + Bravo.   

Here are some pictures to help you differentiate late blight from other tomato diseases.  These pictures are of some of the infected plants I brought into the UConn Diagnostic Lab and were taken by the lab pathologist, Joan Allen.

click on images above to see a larger view

Corn pests
We found the first two fall armyworm moths of the year in a trap in Ellington but no FAW feeding on the young whorl stage corn.  No doubt we=ll start seeing some FAW feeding in young corn next week, at least in Ellington.  The feeding will start as small holes but within days the holes become much bigger and make the plants appear ragged.  Scout for this pest in your corn the same way your would for corn borer except be sure to check the young whorl plantings which FAW seems to prefer for egg laying.  If you find more than 10-15% of the plants infested you should spray once.  SpinTor and Avaunt work at least as well as the synthetic pyrethroids such as Warrior, and sometimes much better. 

Corn earworm pheromone traps were empty in Shelton, East Lyme, Berlin, East Hartford and Ellington this past week, so most farms are not spraying for earworm at this time.  Traps in Northford or North Branford captured an average of 1 moth per night and are on a 5 day spray schedule on fresh silking corn.   

 Here are the CEW thresholds: 

Here is a list of infestations found at different sites while scouting sweet corn this past week. *means that the planting is over threshold and should be sprayed.  MW=mid-whorl, LW= late-whorl, PT=pre-tassel, S=silk.

Town	% infested plants	Stage of planting	ECB moths trapped	CEW moths/N
Shelton	18% 10%	PT LW	0 ECB	0 = no spray
Northford	10%	PT	0 ECB	1 = 5 day schedule
E. Lyme	0%	PT		0 = no spray
Berlin	0% CEW	PT	0 ECB, 0 FAW	0 = no spray
East Hartford	0%	PT	0 ECB	0 = no spray
Ellington	0%	MW	2 FAW	0 = no spray

Pepper maggot
We found stings on hot cherry peppers being used as the trap crop around a field of bell and fryers in Berlin.  The female flies usually start by practicing egg laying without actually depositing any eggs for about a week.  That means that growers who know that they have pepper maggots on their farms should plan on making their first application to the whole field or to just the trap crop towards the end of next week.  Effective materials include dimethoate and Orthene.

If your farm traditionally suffers heavy damage from this pest, then you should plan on making a second and final application about 8-10 days later. 

Pumpkins
Many pumpkin fields are way behind this season due to the cold weather and wet soils that we had during June and early July.  Some vines are just beginning to run, most fields are even younger.  So far, I have not seen any sign of disease on the young plants in most fields except for some Phytophthora in low, wet areas.  Plan to apply your first application of Bravo or another product with the same active ingredient, just after fruit set to help prevent Plectosporium blight from infecting the fruit during this wet season.  Do not apply a systemic fungicide until you detect powdery mildew on the bottom of at least one out of 50 leaves.  You should scout 50 leaves in each field after the plants begin to run.  If there is a tree line on the eastern border of the field which causes the morning dew to sit for a long time before the leaves dry, then this is the best place to check lower leaf surfaces for powdery mildew.    

Cercospora leaf spot on beets and Swiss chard
Cercospora leaf spot can be a problem on leafy greens at this time of year as the temperatures and humidity  begin to climb or simply because the leaves are wet during rain showers.  Leaf spots have red margins and white centers. Management includes crop rotation, not waiting for regrowth on infected plantings after the initial harvest, and spacing successive crops far from early planting.  Bravo type products and the stobilurins are effective at controlling this disease. .

 That's all for this week.  This message will next be updated on Friday afternoon July 24.