UConn Extension Vegetable IPM Pest Message & Reports from the Farm, Friday, Aug

12th, 2016 [Comments/answers in brackets/color by Jude Boucher, UConn Extension].

Jude Boucher – UConn Extension

*Downy Mildew (DM) of Cucurbits – We found DM on cucumbers in Enfield yesterday. All

cucumbers should be treated with an effective product immediately. Some possible choices

include: Ranman, Previcur Flex, Tanos or Curzate. If your cucumbers are due for a powdery

mildew application, you can add the DM product to the spray mix.

Corn earworm (CEW) moths in pheromone traps ranged from 0-7 moths per night this week and

showed a pretty fast rise on some farms near the MA line. Some farms in western CT are still

not spraying, while others are on a 6, 5 or 4–day schedule on fresh silking corn.

Moths per night Spray interval

0-0.2 no spray

0.2-0.5 6-days

0.5-1 5-days

1-13 4-days

>13 3-days

Fall armyworms ranged from 0-3 moth in traps. You should at least scout your pre-tassel stage

corn for caterpillars as this is the last chance to catch an infestation of this pest before the

caterpillars move down to the ears.

European corn borer (ECB) trap captures ranged from 0-2 moths this week. Some farms that

had more than 7 moths last week are just putting on a single application to control the pest this

week, but many farms in the state did not reach threshold or have to spray peppers for the

second generation moths. That flight is over. This just doesn’t seem to be as important a pest

as it once was when we used to catch 300-400 moths per week.

Powdery mildew (PM) – some farms with late-planted pumpkins and winter squash have not

found or sprayed for PM yet. Other farms may be on their second or third application at 10-day

intervals. Again, some of the most effective products from different resistance groups include

Vivando, Torino, Quintec, Proline or Luna Express. They should be mixed with a product that

controls our common fruit rots such as Bravo, Cabrio or Dithane. Sulfur also works well against

PM and would be an effective choice for organic growers, and a good choice for conventional

growers who get to their 5th spray of the season or are looking for a less expensive option.

Ian Gibson, Wellstone Farm, Higganum

The drought stress really exposed several plantings to increased disease and pest damage,

especially in the night shades (solanaceous). Conversely, the cucubrits have been relatively

disease free until just this past week when a few powdery hotspots popped up. Verticillium has

been a patchy problem is a few fields, but seems to be cultivar specific.

Eggplant is suffering mightily from the drought and some cultivars are especially susceptible to

my brand of Verticillium, especially Galine and Orient Express. These two cultivars are also the

primary target of potato leaf hopper (PLH) (OExpress in particular) which isn't very surprising.

On the plus side, Traviata and Orient Charm have resisted both well.

Potatoes were abandoned to their own devices in favor of maintaining tomatoes and other

higher value crops. The PLH vaporized several cultivars and are just picking at other. Banana,

Nicola and Magic Molly are just crispy twigs which the red fingerlings are still standing. This is

the second season in a row that they displayed that tolerance. They were uncovered and

unsprayed, so i have little faith in any sort of appreciable harvest.

PLH damage to susceptible varieties (front). Back rows stood up to PLH much better. Photo by

Ian Gibson

Tomatoes have done well with consistent irrigation, with early blight just now establishing within

my first planting. I have had no anthracnose issues, unlike past years. The hornworms have

been about average and I am seeing some blister beetle, but that is it. I have applied PerPose

over the past two weeks to control the early blight. My last planting did suffer some wind twist

damage.

Peppers are faring the worst in the conditions, despite irrigation, with blossom end rot and sun

scald ruining many fruit. Hopefully the rains will abate this.

Cucubrits are a double edged sword.....there has been negligible disease pressure, but heavy

cuke beetle and squash bug damage. Despite the lack of mildews, we have been spraying milk

and biologicals for the past three weeks. Because of the beetle populations, I have seen a

higher than usual incidence of bacterial wilt.

Brassicas are all under ProtekNet so damage from cabbage worms and flea beetles has been

minimal. In one bed of hakurei turnips that did get exposed, we did get some substantial

damage from cabbage maggot, a pest we infrequently see.

Owen Jarmoc, CT Valley Growers, Enfield, CT [reported by JB]

We found just the first few spots of downy mildew in Owen’s cucumbers yesterday. Long Island

and VT also confirmed DM on cucumber this week. Right now only cucumbers are thought to be

at risk from the strain that has entered New England. L.I. has a sentinel plot with all different

types of cucurbit in it and confirmed that only cucumbers were infected. Cucumbers should be

protected immediately with something that is still effective on this disease, such as: Ranman,

Tanos, Curzate, Previcur Flex. Tests on L.I. in recent years have shown that there is pretty wide

spread resistance to Presidio. Less expensive options such as Dithane and phosphoric acid

type products (i.e. Fosphite) work on some strains of DM. Other options, some of which have

longer harvest restrictions, are listed in the NEVMG (www.nevegetable.org). These products

can be added to the spray mix for powdery mildew if you are about due for another PM spray,

but since DM can defoliate a crop in as little as 7-10 days, you shouldn’t wait too long to make

an application. Remember that the strain that enters CT first each year may be resistant to any

particular fungicide, so you should re-scout your planting 3-4 days after spraying to see if the

symptoms are still advancing: starts as “squareish” yellow spots, which then turn brown, curling

and cupping of older leaves and finally leaf death and defoliation. Apply a different product if

the first does not stop the disease symptoms from advancing.

Peppers – We captured only 2 ECB moths this week in his pheromone traps, down from 7 last

week. He will put on a single application of Coragen to intercept the hatching larvae before they

enter the pods. Hot, dry conditions have caused substantial loss of fruit due to blossom end rot

and sunscald. You can stake peppers to reduce the amount of fruit exposed to sun scald and

daily watering helps move more Ca into the fruit to minimize the occurrence of BER.

Steve Bengtson, Cold Spring Brook Farm, Berlin, CT [reported by J. B.]

I’ve been driving past Steve’s farm all season on the highway and finally got a chance to stop in.

As usual, everything is selling as fast as they can bring it up from the field and stock the

shelves. Location, location, location!

He had nothing but good news monitoring for insects: 0 CEW moths, 0 FAW moths and 0 ECB

moths! A perfect score! No spraying for him this week.

Josh Bristol, Bristol’s Farm Market, Canton, CT [reported by JB]

Josh, his dad Dan, and I checked the traps together and he had similar results to Steve

Bengtson: 0 CEW moths, 0 FAW moths and 1 ECB moth. They sprayed their pre-tassel stage

corn to clean up the FAW infestation from last week, but they were just delighted that they didn’t

have to spray their silking corn again this week – they haven’t had to spray it yet this year. I

was trying to remember, and I know there was one year about 20 years back where most

growers didn’t have to spray for CEW until Labor Day, but this may be the second-best year for

saving sprays and time in corn pest management in the past 30 years.

Since Josh found 7 ECB moths last week he will put a single application of Entrust on his

peppers this week to intercept the hatching larvae before they bore into the pods.

Tomatoes – Some of Josh’s tomatoes had a large black canker at the soil line and were dying,

so I brought a few back to the Plant Diagnostic Lab at UConn. We also found bacterial speck in

the planting. Joan Allen, the UConn Diagnostician, confirmed the speck and also diagnosed the

dying plants as having bacterial canker. The odd part was that this epidemic of canker didn’t

display the usual characteristics that make this disease easy to diagnose in the field: brown

margins on the leaves and birds-eye spots on the fruit (black dot surrounded by a white ring).

Josh will apply copper to try to contain the spread of both diseases.

The margins of the leaves usually turn brown with bacterial canker

Usually you can find a few fruit with birds-eye spots with bacterial canker

Susan Mitchell, Cloverleigh Farm, Mansfield, CT [reported by J. B.]

We found the start of Septoria leaf spot on her tomatoes and she thought she would try

rogueing out the diseased plants and a couple on each side of them to see if she could stop the

spread. There were also a few tomato hornworms in her planting so she may try some B.t. too.

Her young Brassica crops had become infested with cross-stripped cabbageworms in the

greenhouse. She will either hand crush, if time permits, or hit them with B.t.

She also has an outbreak of the margined blister beetle on her Swiss Chard. This minor pest

can also appear on some solonaceous crops like eggplant or potatoes, as well as other greens.

Radiant or Entrust will take it out, but she doesn’t have any so will continue to hand pick the

beetles.

Margined blister beetle

Colin Burson, Pinecroft Farms, Somers, CT [reported by J.B.]

Sweet corn – Pheromone traps in Long Meadow and Enfield captured 2 to 7 moths per night,

putting the silking corn on a 4-day spray schedule. Only 1 FAW moth was captured in Somers.

All young corn had been sprayed with Besiege after the high infestation levels last week, so it

was not scouted this week. The Coragen in the Besiege will provide protection for whorl and

pre-tassel stage corn for at least a week, maybe more.

Peppers – Only 2 ECB moths were captured in traps this week. It has been 2 weeks since they

exceeded the 7-moth threshold, so a single application of Coragen last week will get them

through the small second generation of borers. With the heat this year, we expect a third

generation in September, so we will continue to monitor for this pest.

Cucumbers - They have already sprayed their cucumbers for downy mildew, and we did not find

any in their planting.

Lars and Eric Demander, Clover Nook Farm, Bethany, CT [reported by JB] Sweet corn – Lars captured 0.7 CEW moths per night which calls for treating silking corn on a 5-day schedule. No FAW moths were captured on his farm this week. Tomatoes – Eric found the caterpillar below eating a few of his tomatoes. He thought it was the beet armyworm and said he has seen them in the past and they tend to move from fruit to fruit causing extensive damage. This may actually be the yellow striped armyworm that we have seen on asparagus and peppers the last couple of years. A good caterpillar product such as Coragen, Intrepid, Radiant or Entrust or maybe even a B.t. product should clean them out.

Photo by Eric Demander Brassica – 60% of the plants were infested with imported cabbageworm and cross-striped cabbageworms. He will also apply a caterpillar control to these crops. On his kale, in a separate planting, Lars and Eric had a huge infestation of cabbage whitefly. This pest was recently introduced to this country and we saw it on kalettes last year (cross between kale and Brussel sprouts – its two favorite hosts) on several farms. Since whiteflies are prone to resistance problems and it will take good under-leaf coverage, a high rate of a neonicotinoid, such as Assail, may be the best way to control the pest. This should be

alternated with a different resistance group if control is needed on multiple generations. See the NEVMG for more options.

Cabbage whiteflies (adults and eggs) on underside of kale leaf Dan Slywka, Daffodil Hill Growers, Southbury, CT [reported by JB] Sweet corn – Dan captured 0.5 CEW moths per night in his trap which puts him on a 6-day

schedule on fresh silking corn. He also captured 3 FAW, but there were no caterpillars yet in

his young sweet corn. He will re-scout these blocks next week.

Pumpkins and winter squash – still no powdery mildew on these late plantings. No need to

spray yet. Fruit are just setting, which will start to stress the plants, so maybe next week.

Nelson Cecarelli, Cecarelli Farm, Northford, CT [reported by JB]

Sweet corn – Nelson reported that he is capturing about 1 CEW moth per night which is right on

the border of a 4 and 5 day schedule. That is considered low pressure for a 4-day schedule so

a 5-day will work great.

Tomatoes – he was getting conflicting diagnosis’ from different people of a problem he has on

his tomatoes. I verified that Nelson’s tomatoes have bacterial canker, as he originally thought.

The disease showed all the classic symptoms pictured earlier in this issue: leaf margins brown,

birds-eye spots on fruit, and stem lesions on the vines. He will try a mix of Tanos and copper to

see if he can slow the spread of the disease, while controlling early blight, so that he can

maximize his harvest. The bacteria can enter pruning and harvest wounds and kill plants, so

nothing will completely stop this disease once harvest begins. Hot water treatment can reduce

the chances of stating an infection.

That’s all for this week. The next IPM pest message will be sent on Friday afternoon

August 19th.