Posts Tagged ‘pickling cucumber’

Cucurbit Downy Mildew Update – August 19, 2011

Friday, August 19th, 2011

Bob Mulrooney, Extension Plant Pathologist;

There were reports of downy mildew on pumpkin in northern New Jersey at the beginning of the week. This was sent to the WCU mailing list to make you aware that downy mildew was beginning to appear on more than just pickling cucumber in the area. With the recent thunderstorms, cooler nights and morning fog, conditions will be more favorable for disease development. Maintain your fungicide program at this time. Growers should be aware that the fungicides that have been the most effective on downy mildew on cucumber (namely Presidio, Ranman, and Previcur Flex) will also be very effective on pumpkin, cantaloupe and any other cucurbit. Tanos and Curzate could be added to that list as well for cucurbits other than cucumber. Be aware that Presidio has some plant back restrictions for crops not on the label. The link will take you the new supplemental label: Wheat can be planted 30 days after treatment. This was added in the supplemental label.

Vegetable Disease Updates – August 5, 2011

Thursday, August 4th, 2011

Bob Mulrooney, Extension Plant Pathologist;

Basil Downy Mildew
Basil downy mildew has been seen in nearby NJ. Any sweet basil growers should be scouting for this disease. Phosphite fungicides such as Prophyte have shown the best efficacy for controlling basil downy mildew.

Cucurbit Downy Mildew
Cucurbit downy mildew continues to be seen at low levels in commercial cucumber fields. The dry hot weather has been helping the fungicides to keep it in check. So far we have not seen it move into other cucurbits such as pumpkin. Keep scouting and check the 2011 Commercial Vegetable Productions Recommendations for fungicide suggestions. Once the cooler weather returns, and hopefully some rainfall, look for this disease to increase. Keep up with preventative fungicide applications.

Late Blight
We just received a confirmed report of late blight from Ann Arundel County in MD and in New Brunswick, Canada. Keep on the lookout for this disease on tomato and potato.

Cercospora leaf spot was diagnosed on watermelon last week. Cercospora leaf spot symptoms occur primarily on foliage, but petiole and stem lesions can develop when conditions are highly favorable for disease development. Fruit lesions are not known to occur. On older leaves, small, circular to irregular circular spots with tan to light brown lesions appear. The number and size of lesions increases, and eventually they coalesce and cause entire leaves to become diseased.

Lesion margins may appear dark purple or black, and may have yellow halos surrounding them. Severely infected leaves turn yellow, senesce, and fall off. On watermelon, lesions often form on younger rather than older foliage. Cercospora leaf spot can reduce fruit size and quality, but economic losses are rarely severe. Fungicides such as chlorothalonil (Bravo) and mancozeb including Gavel, as well as the triazole fungicides such as Inspire Super and strobilurins (Cabrio and Quadris) should provide good control of Cercospora leaf spot. As wilthall vine crops be sure to apply in enough water to get good coverage, usually a minimum of 15 gal/A.

Vegetable Disease Updates – July 8, 2011

Friday, July 8th, 2011

Bob Mulrooney, Extension Plant Pathologist;

Late Blight
There have been no new late blight detections in DE or VA on potatoes. The disease apparently is under control and the weather has not been very favorable, especially where the temperatures have been over 90°F. Besides the two finds in DE and VA the only active late blight at present appears to be on Long Island, NY on both potato and tomato.

Downy Mildew on Cucurbits
As most of you know by now downy mildew was found in Sussex County on Tuesday and Dorchester County, MD. Both finds were on pickling cucumber. Since then downy mildew was found in an additional field near Bridgeton, NJ, Talbot County, MD, Wyoming County, PA, and several more cucumber fields in NC. Now is the time to be spraying specific fungicides for downy mildew on cucumbers. Continue to check the IPM pipe website for more information on the spread of downy mildew:

Root Knot Nematode
Root knot nematode can be a very yield limiting pathogen on very susceptible crops like cucumbers and other vine crops, lima beans, snap beans and tomatoes to name a few. They are often worse in very sandy soils or sandy knolls in fields. With the temperatures that we have seen here in DE you can begin to see the swellings or galls on the roots in about 21 days from seeding or transplanting. Plants in infested areas of the field will be stunted and if the plants are dug carefully, if root knot is present, you will see galls of varying sizes on the roots. We have no chemical controls except for vine crops once the nematodes are seen. Vydate should be applied preventatively in fields with known root knot infestations at seeding and/or later when plants are still small. See label for details. Treating early is always better than waiting until galls can be seen.

Root knot galls on baby lima bean roots, 23 days from planting

Pepper Anthracnose
Be on the lookout for anthracnose on peppers. It has been reported in southern NJ. Anthracnose fruit rot can be a very difficult disease to control if it gets established in a field. Fields should be scouted frequently especially if peppers or tomatoes have been planted in the past. It is best controlled by preventative fungicide sprays beginning at flowering. Apply Bravo or another chlorothalonil product every 7 days and alternate with a stroblilurin fungicide (FRAC code 11) like Cabrio or Quadris plus Bravo. If anthracnose fruit rot appears, removing infected fruit from heavily infected areas will help to reduce spore loads and reduce spread if done early and often enough. Fruit will need to be removed from the field and not just thrown on the ground.

Anthracnose on pepper fruit


Cucurbit Downy Mildew Alert – July 1, 2011

Friday, July 1st, 2011

Bob Mulrooney, Extension Plant Pathologist; and Kate Everts, Vegetable Pathologist, University of Delaware and University of Maryland;

Downy mildew was confirmed on seeded cucumbers in Cumberland County, NJ near the city of Vineland. There were no reported downy mildew infections on any transplanted cucurbits in this area. This is the first report of downy mildew on cucurbits in the Mid-Atlantic region this year. Downy mildew has also been increasing in North Carolina the last several weeks. This is a very long leap from NC to NJ if this infection was from air transported spores. Traditionally we can expect downy mildew to arrive here sometime around the 4th of July. DE and MD have sentinel plots for monitoring downy mildew on cucurbits and have been negative for downy so far. These are scouted regularly in addition to reports and samples that we receive from the field. Hopefully we can provide an early warning when it appears here so that timely fungicide applications with downy mildew specific fungicides can be made.

What growers should do:

● Now that downy mildew has been detected in the region growers should be scouting on a daily basis.

● In areas where rainfall has occurred, growers may want to apply targeted fungicides to cucumbers. Tank- mix Presidio, Ranman, or Previcur Flex with a protectant fungicide and alternate sprays with a material with a different mode of action. Because downy mildew has only been found in adjacent states on cucumber, targeted sprays on other cucurbits crops (pumpkin, squash, watermelon, etc.) are not necessary, at this time. Instead scout aggressively and continue a broad-spectrum spray program.

● All abandoned cucumber and summer squash fields should be sprayed with gramoxone or disced under immediately after last harvest to kill the foliage! Abandoned fields left unattended after use will only serve as a source of inoculum for other fields once downy mildew makes its way into our area.

● Please see the 2011 Commercial Vegetable Recommendations Guide for specific fungicide recommendations

● To track the progress of cucurbit downy mildew in the eastern US and to keep up with reports of Downy mildew from other states please visit North Carolina State University’s Cucurbit Downy Mildew Forecasting Center at


Phytophthora Fruit Rot on Cucurbits

Friday, June 24th, 2011

Bob Mulrooney, Extension Plant Pathologist;

Conditions have not been very favorable for fruit rot lately but we always seem to run the risk of scattered thunderstorms and frog-strangling rain events at this time of the year. Phytophthora blight is a tough disease to control, but if you have cucurbits in fields that had fruit rot in the past you are at very high risk if the soil stays saturated even for a few hours. This is a fungus that moves in water and the spores will move where water goes. (Spores will not move more than a few feet in the air.) Some additional cultural controls would be rotation (5 years or more) for watermelons, sub-soiling between the rows before they close to help water drain faster and to keep the fruit out of standing water. Fungicides will only suppress the disease and those that have the best activity are the following: Presidio, Revus, Ranman plus a surfactant (see label), Forum, Gavel and Tanos. Depending on the test, the season, and the location, the efficacy of these fungicides varies. However, proper application of these products will result in better yields than in untreated fields. Remember that Revus and Forum are Group 40 fungicides and have the same mode of action, so they should not be applied in succession. All of these fungicides except Ranman should be tank mixed with fixed copper if the label allows. Fixed copper is not compatible with Ranman plus the surfactant. Good coverage of fruit is very important. For more information on fungicides check the 2011 Commercial Vegetable Production Recommendations.



Downy Mildew Updates – June 24, 2011

Friday, June 24th, 2011

Kate Everts, Vegetable Pathologist, University of Delaware and University of Maryland;

Basil Downy Mildew
Downy mildew on basil has been confirmed in Dunkirk, MD (Calvert County between the DC metro area and Southern Maryland). The infected plants are in a homeowner’s yard, but commercial growers should be on the lookout.

Cucurbit Downy Mildew
As a result of slightly more favorable conditions, Downy mildew on cucurbits is moving northward. Within the last week there have been three reports of downy mildew on CUCUMBER in North Carolina, including one on the border of Virginia. The Cucurbit Downy Mildew forecaster says that disease spread is possible in the mid-Atlantic region, including areas in southern Maryland, the eastern shore, and in Delaware. Scout plants rigorously and monitor the CDM website

Lower leaf surface of a cucumber leaf infected with downy mildew. Courtesy of Gerald Holmes, Valent USA Corporation,

Downy mildew symptoms on upper leaf surface of cucumber.

Downy mildew symptoms on watermelon, note the differences.


Label Additions for Presidio

Friday, May 6th, 2011

Bob Mulrooney, Extension Plant Pathologist;

Valent USA just reported that brassica leafy vegetables, root and tuber vegetables, potatoes and carrots have been added to the Presidio label. The other good news is that the rotation interval for wheat has been reduced from 18 months to 30 days. Hopefully this will be the beginning of the reduction of the other rotational intervals for other crops that follow cucurbits that have limited its use for downy mildew control in pickling cucumbers particularly. The supplemental label is available online here: Presidio is an excellent fungicide for cucurbit downy mildew control and will be another excellent fungicide for control of late blight and pink rot on white potatoes.


September Vegetable Observations

Friday, September 10th, 2010

Gordon Johnson, Extension Vegetable & Fruit Specialist;

Lima Beans
Lima bean harvest is fully underway across the region and the following are some observations in this challenging year. Late May, June, and some early July plantings lost the first set almost completely (heat induced blossom and small pod abortions). The second set is extremely variable and in many fields, economic yields will depend on what happens with the third set. Growers have commented that they are letting fields advance well above the 10% white/dry seed level that is normal for harvest to allow the later set to fill. Some fields are being harvested at the 20-30% dry seed stage (coming from the earlier set). For harvest considerations, it is better to lose a set completely and harvest the later set than to have a bad split set.

There is still considerable dry land lima bean acreage and I am always amazed at how much drought that lima beans can stand without wilting or showing outward water stress. Plants may be smaller but they survive drought and heat very well. Unfortunately, even though lima beans can survive drought, pod set will be limited. Research has shown over and over again that irrigation is necessary to achieve high lima bean yields. In a year such as 2010 where excess heat is also an issue, pod set can be adversely affected, even under irrigation.

We should emphasize again that water is still the most important nutrient for high lima bean yields. In a research plot area where we were looking at residual effects of biofumigant crops and compost this year, we planted snap beans and lima beans in early June as test crops in a dry land situation. After several weeks of drought and heat the snap beans were wilting during the day and were stunted while the lima beans kept on going. To rescue the plots (so that we could get data), we installed drip irrigation between every 2 rows. The snap beans did recover somewhat but with permanently stunted plants, poor bean quality, and a severe split set. In contrast, the lima beans lost the first set but did put on a decent second set and had good plant health and plant size.

Snap Beans
Summer planted snap beans for September harvest are yielding much better than the summer harvested crops. We are seeing yields in the normal 4 ton/A or better range where there was adequate irrigation (compared to summer yields in the 1-2 ton range).

Pickle Cucumbers
Late crops of pickle cucumbers are variable, largely due to stand loss and inadequate water in fields planted during summer high heat periods. In addition, downy mildew has hit a number of later fields adversely, even where fungicides were applied in a timely manner. Pickle harvest should be completed in the next 7-10 days.

I am amazed at how long some watermelon fields have produced this year where attention has been paid to vine health, nutrition, and water. This certainly is the year where you are able to evaluate the yield potential and longevity of main season varieties and effectiveness of pollenizers. On another note, watermelon fields with good weed control (morningglory in particular), had much better later yields.

Tomatoes had a difficult year in 2010 with most fields having much shorter harvest periods due to the extra heat stress. This is especially evident where beds were allowed to dry out at any time during these stressful periods. Somewhat surprising also is the presence of more disease than would be expected in a dry year.

Cucurbit Downy Mildew Update – August 6, 2010

Friday, August 6th, 2010

Bob Mulrooney, Extension Plant Pathologist;

Downy is now present in all three counties in DE on cucumber both pickling cucumber and slicers. I have yet to see it on any other cucurbit so far. Just goes to show you how much this fungus has changed from past years. The ipm PIPE website is predicting continued moderate risk of downy mildew for most of Delaware and Maryland. Maintain spray programs to target downy mildew at this time. See the Commercial Vegetable Recommendations Guide for Delaware for more information and fungicide options.

Cucurbit Downy Mildew Update – July 16, 2010

Friday, July 16th, 2010

Bob Mulrooney, Extension Plant Pathologist;

Wednesday’s rain was a high risk event for cucurbit downy mildew in the region. Be sure downy mildew fungicides are being employed for disease control at this time. There have been no new reports of downy mildew in DE, MD, NJ or PA. That will probably change if this weather pattern continues. Keep current on disease progress by visiting