Posts Tagged ‘tomato’

Early Season Pythium and Phytophthora Control in Pepper and Tomato Crops

Thursday, April 19th, 2012

Andy Wyenandt, Specialist in Vegetable Pathology, Rutgers University; wyenandt@aesop.rutgers.edu

With the dry spring we’ve had thus far, it’s easy to forget about Pythium and Phytophthora! The same question always comes up about this time of year when growers begin to start thinking about transplanting their tomato and pepper crops. “What should I do to help prevent Pythium and Phytophthora?”. In years past, the answer was simple, apply mefenoxam (Ridomil Gold SL, Ultra Flourish, 4) or metalaxyl (MetaStar, 4). Problem solved, right? In the past, that answer was right, but with resistance development in Phytophthora (P. capsici) to both mefenoxam and metalaxyl, the correct answer isn’t so simple anymore. It’s important to remember that both chemistries will work very well as long as resistance hasn’t been detected on your farm.

How do you know if you have resistance? The easiest way is to follow efficacy. If the chemistries no longer provide the control they once did, then there is a good chance you have mefenoxam-insensitive Phytophthora populations present on your farm. There are also lab services which test for resistance. Remember, once resistance develops it can linger around for a very long time. Therefore, proper crop rotation and resistance management is critical before resistance has the chance to develop.

Our options for pre-transplant applications include a Ranman (cyazofamid, 21) drench one week before transplanting for Pythium in tomatoes as well as Previcur Flex (propamocarb HCL, 28) for the suppression of Pythium and Phytopthora in tomatoes and peppers. Phosphite fungicides, such as ProPhyt and K-Phite (FRAC code 33) can also be applied as a pre-transplant drench in the greenhouse. Additionally, there are a number of biologicals such as Trichoderma, Streptomyces, and Bacillus products which can also be used in the greenhouse to help suppress soil-borne pathogens. Remember, the biologicals need to be applied without conventional fungicides.

At transplanting applications now include Ranman (cyazofamid, 21) in the transplant water or through drip irrigation for Pythium control. There is a section 2ee for the use of Previcur Flex (propamocarb HCL, 28) + Admire Pro (imidacloprid) in transplanting water for Pythium control. Presidio (fluopicolide, 43) now has a label for drip application for Phytophthora control when conditions are favorable for disease development. Additionally, phosphite fungicides, Pro-Phyt and K-Phite (FRAC code 33) can also be applied through drip irrigation at transplanting to help suppress Phytophthora blight. Unlike in the past, there are a number of good options for early season control of these pathogens, it just takes a little bit more planning ahead of time. For further details on use and crop labeled please refer to the specific fungicide label. Remember the label is the law.

Updated Fertilization Recommendations for Drip Irrigated Crops

Thursday, April 19th, 2012

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

Extension specialists in the Mid-Atlantic have updated fertilizer recommendations for drip irrigated plasticulture production of crops in the Commercial Vegetable Production Recommendations. The following are recommendations for watermelons and tomatoes.

Suggested Fertilizer Program Using Trickle Irrigation for Watermelons

Days After Planting

Daily

Cumulative

Nitrogen1

Potash1,2

Nitrogen1

Potash1,2

——————–lbs/A——————–

Preplant3

25

50

0-14

1.0

1.0

39

64

15-28

1.5

1.5

60

85

29-56

2.0

2.0

116

141

57-78

1.5

1.5

137

166

79-93

1.0

1.0

150

175

1Adjust rates accordingly if you apply more or less preplant nitrogen and potash.
2Base overall application rate on soil test recommendations.
3Applied under plastic mulch to effective bed area using modified broadcast method. Adjust as needed.
Note: recommendations are based on 8 foot bed centers. If beds are narrower, fertilizer rates per acre should be adjusted proportionally. Drive rows should not be used in acreage calculations.

Suggested Fertigation Schedule – Fresh Market Tomatoes

Days After Planting

Daily

Cumulative

Nitrogen1

Potash1,2

Nitrogen1

Potash1,2

——————–lbs/A——————–

Preplant3

50

125

0-14

0.5

0.5

57

132

15-28

0.7

0.7

67

142

29-42

1.0

1.0

81

156

43-56

1.5

1.5

102

177

57-77

2.2

2.2

148

223

78-98

2.5

2.5

201

276

1Adjust rates accordingly if you apply more or less preplant nitrogen and potash.
2Base overall application rate on soil test recommendations.
3Applied under plastic mulch to effective bed area using modified broadcast method. Adjust as needed.
Note: recommendations are based on 6 foot bed centers. If beds are narrower, fertilizer rates per acre should be adjusted proportionally. Drive rows should not be used in acreage calculations.

Additional recommendations can be found in the Recommendation which is also online at this site: http://ag.udel.edu/extension/vegprogram/publications.htm.

Tomato Pinworms Can be a Problem for Greenhouse Growers

Thursday, April 5th, 2012

Cory Whaley, Sussex Co. Extension Ag Agent; whaley@udel.edu and Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu

Tomato pinworms have recently been found infesting tomatoes in a greenhouse in Delaware. According to Jerry Ghidiu, an entomologist with Rutgers University, once pinworms become established they can move quickly through the house and threaten the entire crop. He stated that tomato pinworm is difficult to control and it is best to catch it early; multiple applications of insecticides will be needed for control. First instars are foliar feeders and mine into the leaf. Older larvae may fold the leaf over itself, or stick leaves together. In severe infestations all leaves are infested and the crop may have a burnt appearance. Larvae can then move into the fruit, making control much more difficult. Larvae will leave small pinholes at entry points. Pinworm can complete its life cycle in 28 days and there may be more than 7-8 generations per year. Adults are small gray moths and once adults are seen, infestations are severe. Pheromone traps can be used to detect and monitor the moths.

Entomologists in the region recommended Pylon as the best control labeled for greenhouse tomato use to control this pest. They also noted Entrust as another material to consider especially for organic production; however, it carries the following restriction: “Do not apply to seedling fruiting vegetables (which includes tomatoes) and okra grown for transplant within a greenhouse, shade house, or field plot.” As with all materials, you need to read the label for rates and restrictions before applying. Please refer to the Commercial Vegetable Production Recommendations for additional products to use in a rotation.

 Tomato pinworm larva

 Tomato pinworm larva on a damaged leaf

Tomato pinworm frass and leaf damage

Burnt appearance and leaf folding caused by tomato pinworm feeding

Yellow Shoulders in Tomato a Big Problem This Season

Thursday, August 4th, 2011

Jerry Brust, IPM Vegetable Specialist, University of Maryland; jbrust@umd.edu

A very wide spread problem this year in tomatoes, especially some of the large-sized fruit, is yellow shoulders. Yellow shoulders is characterized by areas at the top of the fruit (shoulders of fruit) that stay green or yellow and as the fruit ripens tend to turn a more intense yellow. These areas will never ripen properly. The area beneath the yellow shoulders is firm and poor tasting. Unfortunately the cause of this problem is complex involving the environment and plant physiology and there is no cure, but there are things that can be done to ease the symptoms. One of the main causes is one we have had lots of and one we can’t do much about and that is intense heat (this past July was the hottest month on record for our area). High temperatures prevent lycopene production (red pigment of the tomato fruit) most often in the shoulders of tomato, as this part is more commonly exposed to the direct rays of the sun. We measured fruit (pulp) temperatures of between 86o and 105oF morning through evening hours in July. When temperatures are greater than 85-88oF lycopene is not produced. Temperatures need to drop below 85oF before it is consistently produced.

Inside the plant we see a reduction in potassium (K) just before yellow shoulders is seen. This year in our tissue testing we saw drops in K of 3-4% in a matter of weeks going from 4-6% (which is good) to 2-3% (which is poor). Usually within a week or two of this drop we see yellow shoulders start up. There are also drops in calcium (Ca), nitrogen and at times magnesium (Mg) as we move into mid-July and early August. All this is related to stress on a plant that has a full fruit load and the stress could be too little water, too much heat (most common), or high amounts of plant disease or insect problems. We see the same problems in high tunnels; only we see them a month earlier than in the field. For now, best recommendations are to add more potassium and calcium to plants and make sure plants are well watered. You can add either nutrient through the drip or as foliar sprays. Foliar sprays will help, but it is difficult to raise the potassium levels 2-4% points as would be needed. I have found that boron also plays a role in helping with the uptake of K, Ca, sulfur and Mg, but all the data are not in at this time to make a recommendation. Yellow shoulders is also a varietal problem, as some varieties are more prone to the problem than others. One unusual way of avoiding the problem all together is to harvest tomatoes when pink color is first seen and let the fruit ripen at room temperature in the dark. Because the lycopene is produced as the fruit ripens it is often possible to avoid yellow shoulders by removing the fruit from the high temperatures and other stresses.

 

 

Various forms of yellow shoulders on red tomato fruit

 

Vegetable Disease Updates – August 5, 2011

Thursday, August 4th, 2011

Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu

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.

Watermelon
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.

Summer Vegetable Plantings for Fall Harvest

Thursday, July 28th, 2011

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

Plantings for fall harvested vegetables are underway. Timing these plantings can be a challenge, especially where multiple harvests are needed. Plantings from mid-July through the end of August may be made, with cutoff dates depending on the crop, variety, and season extension methods such as row covers, low tunnels, and high tunnels.

These plantings can be divided into 2 groups: 1) warm season vegetables for harvest up to a killing frost and 2) cool season vegetables for extended harvest in the fall.

The three main factors influencing crop growth and performance in the fall are daylength, heat units, and frost or freeze events. A few days difference in planting date this time of year can make a big difference in days to maturity in the fall.

Warm season vegetables for fall harvest include snap beans, squash, and cucumbers. July plantings of sweet corn can also be successful to extend seasons for farm stands. Mid-July plantings of tomatoes and peppers also are made for late harvests, particularly in high tunnels.

Cool season vegetables for fall harvest include cabbage, broccoli, and cauliflower; the cole crop greens, kale and collards; mustard and turnip greens; turnips for roots; spinach; beets; lettuce; leeks; green onions; and radishes.

To extend harvest in the fall, successive plantings are an option. However, days between plantings will need to be compressed. One day difference in early August planting for a crop like beans can mean a difference of several days in harvest date.

Another option to extend harvest in the fall is with planting different maturing varieties at the same time. This is particularly successful with crops such as broccoli and cabbage where maturity differences of more than 30 days can be found between varieties.

Another way to get later harvests is by use of row covers or protecting structures. This can allow for more heat accumulation and will aid with protection against frost and freezes. Decisions on what type or combination of covers/protection to use and when to apply the protection will influence fall vegetable maturation and duration of harvest.

A final factor for summer planting for fall production is on planting cutoff dates. For example, a crop such as cucumber may produce well with an August 2 planting but poorly with an August 8 planting; broccoli has a wider planting window than cauliflower; turnip greens have a wider planting window than kale.

Tomato Leaf Roll Problems

Friday, July 15th, 2011

Jerry Brust, IPM Vegetable Specialist, University of Maryland; jbrust@umd.edu

Over the last few weeks there have been many reports about tomato leaves curling, sometimes severely, in growers’ fields. It starts with upward cup­ping at the leaf margins followed by inward rolling of the leaves (Photo 1). Lower leaves are affected first, and can recover if environmen­tal conditions and cultural factors are adjust­ed to reduce stress. Not all leaves on a plant roll, but eventually the rolling can involve most leaves on a plant and last through the season. In severe cases, whole plants can be affected. The margins of adjacent leaflets may touch or overlap (Photo 1). Rolled leaves become rough and leathery but are otherwise normal in size and appearance. There is no discoloration of leaf veins associated with this problem. The good news is that leaf roll rarely affects plant growth, fruit yield, or fruit quality.

How bad leaf roll gets appears to be very cultivar dependent. Cultivars selected for high yield tend to be the most susceptible. Indeterminate cultivars seem to be more sen­sitive to this problem than determinate cultivars. Leaf roll is often seen just after plants are heavily pruned during dry soil conditions. If the tomato plant’s top growth is more vigor­ous than root growth and we are hit with a dry hot period the foliage may transpire water faster than the root system can absorb it from the soil, and the plant will respond by rolling its leaves to reduce the transpiration surface area. Another cause of this disorder includes growing high-yielding cultivars under high nitrogen fertility programs. Oddly enough leaf roll disorder also has been found to be caused by excess soil moisture coupled with extended high temperatures.

It has been found that sugar and starch accumulate in the lower leaves causing the leaf to roll; the more they accumulate the worse they roll. Leaf roll is usually a problem we see when we have hot dry conditions in June or July, when plants are most actively growing. Because leaf roll will seldom affect yield it is a problem that not much should be done about other than making sure it is not some other more severe problem (some viruses can look similar to tomato leaf roll, but if the symptoms suddenly appear and involve many of the plants in a field and their lower leaves it is probably leaf roll). You can reduce symptoms by maintaining consistent, adequate soil moisture (~1 inch per week during the growing season, which will also help with calcium up-take reducing blossom end rot problems). Growers also should not prune heavily during hot dry conditions or over-fertilize with nitrogen.

Photo 1. Tomato plant with mild leaf roll of lower leaves

Vegetable Disease Updates – July 8, 2011

Friday, July 8th, 2011

Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu

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: http://cdm.ipmpipe.org.

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

 

Late Blight Report

Friday, July 1st, 2011

Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu

Late blight caused by the fungus-like organism, Phytophthora infestans, was confirmed this week in DE, eastern shore VA, and the South Fork on Long Island, NY on potato. See the Potato Disease Advisory. Late blight was confirmed on tomato on Long Island, NY. Growers should be checking fields daily and maintaining preventative fungicide sprays. The weather conditions have been favorable the past few days but the hot weather forecasted for this weekend should help reduce the threat. The Delaware find was a small area at the end of a field next to woods and under power lines that obstructed the aerial application of fungicide applied to the whole field. Late blight specific fungicide has been applied.

For more information on controlling late blight on potato and tomato, see the 2011 Commercial Vegetable Recommendations. In addition to the information in the Commercial Veg Recs guide there is a very good table on fungicides for late blight on tomato and potato from Cornell University summarized by Dr Tom Zitter: http://vegetablemdonline.ppath.cornell.edu/NewsArticles/2011PotatoFungicide_emphasis_on_late%20blight.pdf

http://blogs.cce.cornell.edu/cvp/files/2011/06/2011-Tomato-Fungicide-Roster-and-Ratings-chart.pdf

 

Physiological Leaf Cupping and Rolling in Vegetables

Friday, July 1st, 2011

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

Leaf cupping and rolling in vegetables can be caused by virus diseases, aphid infestations, herbicides and growth regulators. However, late spring and early summer is the time of the year that we often see leaf cupping and rolling disorders appear in vegetable crops that are not related to pests or chemicals. This can be seen in tomatoes, peppers, potatoes, watermelons, beans, and other crops. This is a physiological disorder that may have many contributing factors.

In tomatoes, leaf roll starts at the margins which turn up, then roll inward, most commonly on the lower leaves. Upward cupping is also found commonly in watermelons and potatoes. Beans, peppers, and other vegetables may cup downwards. Leaves may stay in this rolled or cupped state for a short period of time and then return to normal, or they may remain permanently rolled or cupped. Rolled leaves may become thicker but are otherwise normal. Physiological leaf roll or cupping is often variety dependent with some varieties being more susceptible than others.

There are several possible causal factors for physiological leaf roll or cupping. Water relations are suspected in many cases where there has been a reduction in water uptake or increased water demand placed on the plant. The plant responds by rolling the leaves which reduces the surface area exposed to high radiation. High temperatures, excessive pruning, cultivation, and vine moving activities may also trigger leaf rolling. High nitrogen fertility programs followed by moisture stress may also trigger this type of leaf roll. Inadequate calcium moving to leaf margins may also cause a different type of leaf cupping. This is also related to interrupted water movement.

In most cases, yields are not affected by physiological leaf rolling or cupping. However, growers may choose to select varieties that are less susceptible to this disorder.