• Corn earworm alert

• Fall armyworm alert

• European corn borer pepper sprays

• Dealing with late blight infested fields

• Powdery mildew and Plectosporium on cucurbits

• Downy mildew on Long Island

I'll start by apologizing for the double pest message trouble we had the last two weeks. In my haste before leaving on vacation on July 24^th, I forgot to attach the message when I sent it over to the web master for posting on the UConn IPM Web Site.  Then, because it never rains but it pours, the 20-year-old code-a-phone message machine chose this week to die, so the pest message wasn't even available by phone.  Again, my apologies.

Corn earworm
The number of corn earworm moths captured in pheromone traps around the state went way up in many locations, but experienced only a slight rise at some farms, and no increase at all at one isolated farm in Falls Village which did not capture any CEW and is still not spraying silking corn.  However, fields in Northford, Wallingford, and Glastonbury captured between 40 and 50 moths per night earlier this week and are on a 3 day spray schedule on fresh silking corn.  When the numbers are this high you don't want to stretch the interval at all no matter what insecticide you are using on your corn.  Also, if the weather forecast predicts rain on the third day when you are due to spray, then you should go in on the second day instead or you will see meat in your corn at harvest if you wait until the 4^th day. 

Farms in Shelton and East Hartford captured 25 moths per night and are also on a 3day spray schedule on fresh silking corn. The farm in Northford also dropped off to 25 moths per night later in the week but is maintaining the 3 day schedule.  Farms in North Branford, New Milford, Berlin and Ellington captured between 1.3 and 9 moths per night and are on a 4 day spray schedule on fresh silking corn.  If you're not running traps on your farm, then you probably want to be on a 3 day spray schedule at this time, to be on the safe side. 

There are many synthetic pyrethroid insecticides that can provide great control of high levels of CEW: including Warrior, Mustang, ProAxis, to name just a few.  If you are capturing more than 13 moths per night on your farm and have been using spinosad, the active ingredient in  SpinTor or Entrust, or a B.t. product like XenTari for low CEW pressure, now is the time to switch to a synthetic pyrethroid or you will start to find caterpillars in the ears at harvest.

Fall armyworm alert
Pheromone traps for FAW captured between 0 and 28 moths this past week, which means that you should be scouting your young whorl and pre-tassel stage corn for this pest on a weekly basis.  The real story however, was that field infestations around the state ranged from 2 to 56% of the plants infested with caterpillars.  Most farms where I scouted corn, had infestations above the 10-15% action threshold or approaching it. I tend to use the lower 10% infestation level for pre-tassel stage corn. One farm in Shelton had 32% of the pre-tassel stage plants infested with very small FAW larvae that had just hatched.  Remember that these larvae will make a beeline for the ear as soon as the tassel pops open and before you make your first silk spray.  If, you don't want to bother scouting early and mid-whorl stage corn, which can get pretty chewed up by large populations of this pest, then you should at least scout the blocks that are in the pre-tassel stage, so that you can clean them up before the caterpillars migrate to the ear zone. 

To scout, look at 10 plants in a row, in 5 different locations in each block, for a total of 50 plants.  Take the number of infested plants that you find and multiply it by 2 to get the percent of infested plants in the field and spray if you have more than 10-15% infested plants. Remember that we usually get more consistent performance with SpinTor, Entrust or Avaunt on FAW than with the synthetic pyrethroids.  

European corn borer pepper sprays 
One trap in Berlin failed to capture any bore moths in traps this week, but Farms in Shelton, Northford, and East Hartford captured between 4 and 15 ECB moths per week.  Both the Shelton and Northford sites were over the 7 moth per week threshold for spraying peppers, so applications should begin at those sites one week after capturing 7 moths.  This gives the moths time to mate, and lay eggs, which in tern need almost a week to hatch, so you still have plenty of time to kill the hatching larvae before they reach the pods. Growers in the valley who are not running traps for ECB should start spraying peppers after this weekend (Aug 9^th).  Growers in the western or eastern hills may not need to start spraying peppers for another week or two. The UConn IPM program recommends alternating between the insect growth regulator Intrepid and SpinTor for borer control.  Wait 10-14 days after a Intrepid application before applying SpinTor, and 7 days after SpinTor before applying Intrepid.  Both these materials can be applied within one day of harvest.

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	32% FAW*	PT	15 ECB, 3 FAW	25 =  3 day schedule
	21% FAW*	MW
	56% FAW*	EW
Northford	20% FAW* 15% FAW*	PT MW	9 ECB, 28 FAW	25 =  3 day schedule
North Branford I & II				9 = 4 day schedule
Glastonbury				50 = 3 day schedule
Berlin	22% FAW*	MW	0 ECB, 0 FAW	6.5 = 4 day schedule
	4% FAW	LW
	10% FAW	MW
East Hartford	25% FAW*	MW	4 ECB, 20 FAW	20 = 3 day schedule
New Milford	10% FAW	MW	3 FAW	1.3 = 4 day schedule
	14% FAW*
Ellington	2%FAW	PT	2 FAW	4 = 4 day schedule
Falls Village	4% FAW	EW-MW		0 = no spray

Dealing with late blight infested fields
(Most of the information that follows comes from articles by Meg McGrath, the plant pathologist at Cornell=s Long Island Research Station).
All tomato and potato fields should be being sprayed for late blight at this time on a 5 to 7 day schedule.  The schedule can be stretched to 10 days if the weather remains hot and dry between sprays. Growers that are alternating between the systemic fungicides Tanos/Curzate, Previcur Flex, or Presidio, and also adding a protectant fungicide such as a maneb/mancozeb type product, or a Bravo or generic Bravo-like product, or Ranman, have been able to control this disease pretty well.  Presidio has a 2dh restriction on tomatoes, while Tanos has 3dh, and Previcur Flex has 5dh.  Restrictions are usually longer on potatoes.  Presidio is not registered for potatoes.  Gavel is the only late blight material that comes with a pre-mix of an effective systemic and a protectant, but carries a 5dh restriction on tomatoes and 3 dh for potatoes.  UMass is reporting that some organic farms that started early with copper sprays have had some degree of protection from this disease, although it is not considered to be a very effective material.

Tomatoes in greenhouses and high tunnels are at less risk to late blight, but can still become infected.  Previcur Flex, Curzate and some copper and mancozeb products can be used in greenhouses and tunnels.

It seems many growers did not heed the warnings about how fast this disease can kill a field and that a different fungicide program was needed this year to control this disease.  Some organic growers made an informed choice not to spray their fields.  Tomato and potato plantings on organic farms and on many large conventional farms that did not adjust their spray schedule to the late blight threat in time this season have already been destroyed by this disease.  Others have too many plants infected and sending off spores to survive much longer and should be destroyed. 

The spores can spread for many miles on the wind during cloudy and rainy weather. Sanitation is an important part of controlling this disease.  When late blight is first found on a few isolated plants, remove those plants from the field, bury them, or place them under a tarp to kill the spores and contain the spread of the disease.  This will give your fungicide program a fighting chance.  Tomato plants can be cut at the base or pulled from the ground to kill the plants rapidly.  Kill early plantings that are heavily infected when harvest becomes limited to help protect late plantings.  Large potato fields can be sprayed with Diquat or paraquat, or flamed, or mowed to kill the vines.  If plowing or discing is used to kill large sections of infected plants, the field should be sprayed first to help minimize the spread of spores.  Spores can also move on equipment or personnel.  Work in infected field late in the day and do not let workers reenter uninfected blocks before they have changed and washed their clothes. Pressure clean equipment after working in infected areas.

Spores are deactivated by ultra violet light on warm sunny days and require living plant material to reproduce.  Potato fields that are heavily infected with the disease should be killed to protect the tubers.  Allow the vines to dry for two weeks after vine kill or mowing to allow the spores time to die.  Dig potatoes on a warm sunny day to minimize infection of the tubers.  Be aggressive in culling potatoes prior to storage.  Anything that looks suspicious should be culled.  If tops are dried and dead, or mowed off, tubers can be dug over time to extend harvest. Some experts are recommending storing the tubers in the ground until they are ready to be marketed, if possible.  Do not wash potatoes that are harvested unless absolutely necessary.  If tubers must be washed, UVM recommends Storox (Oxidate) for organic growers or chlorine at labeled rates.

Late blight will not survive the winter on any part of the tomato plant, in the soil, or on alternate weed  hosts, such as nightshade.  Tomato fields can be harrowed or plowed down as usual at the end of the season before planting a cover crop. Tomato stakes can be stored under a tarp in the sun for a week or two to help deactivate spores.  Late blight will only survive the winter in infected tubers.  Potato growers must take great care next year to manage volunteer plants that emerge from this year=s fields or this whole late blight cycle can start all over again.  Tubers can be left on the surface and will be killed by freezing temperatures this winter.  However, buried tubers can produce infected plants next year that must be destroyed early before the spores start to spread.  Organic grower may want to plan to disk 2009 potato fields several times next spring and early summer before planting a late-season cash crop. Conventional growers should be prepared to kill volunteer plants with post-emergence herbicides or cultivation equipment.

Powdery mildew and Plectosporium on cucurbits
Powdery mildew is now present in most fields that I have scouted with growers and Plectosporium blight was also common this week.  Plecto can be found by separating the leaves of the canopy and looking at the large main vines that run along the ground in a pumpkin field.  You're looking for many small, white, diamond or lense-shaped spots on the stems.  Strobiluron fungicides (Pristine, Cabrio, Quadris, Flint, etc.) and Bravo type materials are the most effective products for Plecto.  Powdery Mildew is almost always worse on the underside of the leaves, before it spreads to the top side, so we need systemic fungicides to help control it effectively early in the season.  However, systemic fungicides are extremely susceptible to resistance, so each family or group should only be used a single time each season and then you should rely on sulfur for additional sprays. 

So here is my suggested program for pumpkins and long-seasoned winter squash, as long as downy mildew doesn't show up on these crops:

• 1^st spray - Pristine + Manex

• 2^nd spray - Procure (top rate) + Bravo

• 3^rd spray - sulfur + Bravo

• 4^th spray - sulfur + Bravo

• 5^th spray - Bravo  

Use a 10 day spray schedule, but shorten it to 8 days if it stays wet.   Helena and Field Works sell a type of powdered sulfur called Microthiol Dispress which mixes up much better than other brands of dry sulfur, some of which can be tough to get out of your sprayer.