Late blight on Connecticut farms
The late blight that was distributed to thousands of home gardens on plants sold from big box stores throughout the Northeast is reaching commercial farms: 5 of the last 10 farms I visited this week in the middle and upper portions of the Connecticut River Valley have had late blight.  This disease has been confirmed by the diagnostic lab at UConn.  This is an air-borne Phytophthora, that primarily affects tomatoes, potatoes and weeds such as black and bittersweet nightshade.  It moves long distances on the wind, just the way downy mildew or powdery mildew does.  You should assume that it is on the tomatoes and potatoes on your farm or will in the next week or so.  It is capable of killing your entire planting in as little as 2 to 5 days if conditions remain cool and wet.  All commercial growers should be spraying for late blight at this time.  Be aware that some of the previous products recommended for late blight control are not fully effective and should be mixed with a systemic fungicide or a contact fungicide specific for water molds and late blight.  All systemic materials should be mixed and applied with a protectant such as chlorothalonil, the active ingredient in Bravo and several other generic products, or a maneb/mancozeb type product like Manzate.  Be aware that maneb and manzate products have a 5 day-to-harvest (dh) restriction on tomatoes so should not be used after the first fruit begin to color.  Also, it is critical that you alternate between systemic materials in order to prevent resistance which can build up during a single season if a product is overused.  That means you need to purchase two systemic products or even protectant products specific for late blight. 

List of effective late blight fungicides
I'll start with systemic materials because these products will translocate throughout the plant to some degree and provide the best spray coverage and protection. Growers who have not staked or trellised their tomatoes for better spray coverage should make sure to include a systemic product with every spray.  Some of these products will have longer dh restrictions than you are used to for a crop that must be picked as frequently as tomatoes.  Adding something to strengthen the Bravo throughout harvest will probably be the difference between having tomatoes this year and not having tomatoes.  Try to pick products with the lowest dh restrictions to facilitate harvesting. 

Curzate is a systemic Group 27 Fungicide that can provide up to 2 days of kickback or burnout action when temperatures are cool, but not if temperatures are over 80 degrees. That means it will actually destroy late blight lesions that have formed up to 2 days earlier, which can make all the difference when dealing with a disease that spreads as quickly as this one does. The problem is that it only lasts a few days and should be followed by an application of a different mix in only 5 days. Curzate has a 3 dh restriction on tomatoes and 14 dh on potatoes.  It should be mixed with chlorothalonil or manzate/maneb. 

Tanos is a premix of the active ingredient in Curzate and a group 11 stobiluron fungicide similar to Flint, Quadris or Cabrio.  The group 11 fungicide is added to help stretch the activity of the Curzate active ingredient.  Again you should make your next application 5-7 days later.  Tanos has a 3dh restriction on tomatoes and 14dh on potatoes.  It should be mixed with chlorothaonil, maneb/mancozeb or copper.   

Previcur Flex is a systemic product that has performed well on downy mildew on cucurbit crops, which is another water mold and a near relative to late blight. It has a 5dh restriction on tomatoes and 14 dh restrition on potatoes. It can also be used twice on greenhouse tomatoes and has just a 2dh restriction in the GH.  Previcur Flex should also be mixed with chlorothalonil or maneb/mancozeb in the field, but not in the greenhouse. 

Presidio is a new systemic fungicide that has not yet been widely tested against late blight in the field, but which is suppose to work real well on other water molds. It also claims to have some curative or kickback action.  It has a 2dh retriction on tomatoes but is not registered on potatoes. The label calls for 10 day intervals between sprays and recommends mixing it with a protectant, but doesn=t specify which ones are safe to prevent phytotoxicity. 

Gavel is a premix that contains both a systemic and an mancozeb type product, so it does not need to be mixed with another protectant.  However, the label states that a Latron surfactant should be added for maximum spray coverage during high disease pressure. 

Ranman is not a systemic, but is labeled specifically for late blight and has performed well in tests and in previous years on some strains of downy mildew in Connecticut.  Best of all, it has a 0dh restriction on tomatoes and just a 7dh restriction on potatoes.  The label recommends adding either an organosilicon adjvant or a non-ionic surfactant for maximum spray coverage.    

You should also be aware that the other strobiluron group 11 fungicides such as Flint, Quadris, or Cabrio, are not rated very highly for late blight control and are not expected to hold off the disease with the pressure we are facing this season. Copper is really the only choice that organic grower have but unfortunately it also is not rated highly against late blight. 

European corn borer and fall armyworm
There were no ECB moths in pheromone traps in Shelton or Berlin this week, but traps in East Lyme captured 5 moths.  We are between generations for this pest, but there are still some pre-tassel and late whorl stage plantings that are near threshold or over the threshold of 15 % infested plants.  Once you hit those fields with one pretassel spray you should be free of ECB until late next month.  The first FAW moth was captured in Northford this past week but other traps in Berlin and South Windsor were empty and I didn't come across any FAW feeding injury while scouting corn for borer this week.  If you are not setting up pheromone traps for this pest continue to scout your whorl and pretassel stage corn on a weekly basis. 

Corn earworm
Pheromone traps in Shelton, East Lyme, East Hartford and South Windsor were all empty this week and those farms are not spraying silking corn for earworm at this time. There was a little activity in East Lyme and East Hartford last weekend that dropped off to no activity this week.  Berlin captured an average of 0.2 moths which puts them on a 6 day schedule for fresh silking corn while Northford captured 1.6 moths per night and is on a 4 day schedule on fresh silking corn. 

Here are the CEW trap thresholds: 

moths per night		recommended spray interval
0-0.2		No spray
0.2-0.5		6 day schedule
0.5-1		5 day schedule
1-13		4 day schedule
>13 moths		3 day schedule

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	16%* 18%	PT LW	0 moth	0 = no spray
E. Lyme	28%* 8%	PT LW	5 ECB	0 = no spray
Northford	10%* 10%	PT PT	1 FAW	1.6 = 4-day schedule
Berlin	12% 10%	GT LW	0 ECB, 0 FAW	0.2 = 6-day schedule
East Hartford				0 = no spray
South Windsor			0 FAW	0 = no spray
Ellington	0%	PT	set up FAW	0.1 = no spray
New Milford	8% 0%	PT LW	set up

No pepper maggots
There was no sign of pepper maggot in Berlin on ammonia baited traps or on cherry peppers around the perimeter of the field.  All this cold weather seems to have slowed them down a little this year.

Higher potato leafhopper populations
One grower had plenty of potato leafhoppers on his potatoes and eggplant this week and both crops required a spray.  Treat potatoes if you find 1 adult or 15 bright green nymphs per 50 compound leaves. The threshold for eggplant is 1 per leaf.  On eggplant you want to choose something, such as Provado, that will not disrupt the predators and parasites that help control spider mites, aphids, and CPB. Spray seedling beans before the 3 leaf-stage if you find more than 2 PLH/foot of row or between the 3-leaf and bud stage if you find 5/foot of row.  The cheapest way to control this pest on beans is to use as little a 1/4-rate of dimethoate.                     

Fusarium/Phytophthora
As you can imagine with all this wet weather we are seeing a whole lot of soil-borne diseases around.  These include Phytophthora, Fusarium and to a lesser extent Pythium.  The best strategy for any of these diseases is a combination of water management and crop rotation. Use a sub- soiler or Zone Builder to break up plow pans that have formed in your fields so that the water can drain through the soil and does not accumulate until you have standing water on the surface.  There are also many other water management suggestions in the article on Peppers and Phytophthora on the UConn IPM Web Site.  One grower lost most of the seedling pepper and tomatoes that he planted to Phytophthora in a field that had been in pumpkins last year and corn for many years before that.  This simply illustrates once again that it doesn=t take long for Phytophthora to spread across a new field with susceptible hosts when the years are wet like last year and this year.  

That's all for this week.  This message will next be updated on Friday afternoon July 17.