Vegetable Notes 2026 Vol. 38:13

Blossom End Rot

Blossom end rot is characterized by dark brown or black sunken areas at the blossom end of the fruit. The lesions are a direct result of a localized calcium deficiency at the blossom end. The dead tissue is initially brown or white and leathery but often becomes colonized by the saprophytic fungus Alternaria alternata, which only infects dead tissue and produces fuzzy black sporulation. Although calcium deficiencies in the soil are sometimes responsible for blossom end rot, much of the time, blossom end rot is the result of plant water stress. When temperatures increase, so does water demand, and developing fruits have high calcium needs. Calcium is taken up primarily through the water-conducting tissues of the plant, so when the soil is dry, or, counterintuitively, over-saturated, or if the plant’s roots are compromised and the plant isn’t taking up water, calcium deficiencies develop. The blossom end of the fruit is the last to accumulate calcium, so this is where deficiencies appear. Signs of blossom end rot typically appear two weeks after the deficiency in the plant has occurred. 

Blossom end rot can be prevented by regular watering to avoid extreme fluctuations in soil moisture. In high tunnel tomatoes, it is recommended to use more than one drip line per bed to ensure that the entire extensive root system is able to supply sufficient water to the lush foliage. Be careful to avoid overwatering, though, as this can lead to root rots or other physiological disorders. Use of soil moisture monitors can help dial in watering needs. High soluble salts, low calcium, and high cation levels (potassium, magnesium or ammonium) in the soil may also contribute to blossom end rot. These other cations may out-compete calcium on soil exchange sites when they're too concentrated in the soil, making calcium unavailable to the plant.

Leaf roll is usually a reaction by the plant to conserve water by reducing the surface area exposed to solar radiation. This disorder is often seen just after plants are heavily pruned under dry soil conditions, but oddly enough, leaf roll disorder has also been found to be caused by excess soil moisture coupled with extended high temperatures. If the tomato plant’s foliar growth is more vigorous than root growth and we are hit with a hot, dry period, the foliage may transpire water faster than the root system can absorb it from the soil, and the plant’s reaction is to roll it’s leaves up to reduce transpiration. This disorder primarily affects lower leaves. Leaf rolling can also result from growing high-yielding cultivars under high-nitrogen fertility programs. Cultivars selected for high yield or early ripening tend to be the most susceptible and indeterminate cultivars are more sensitive than determinate. The good news is that leaf roll rarely affects plant growth, fruit yield, or fruit quality. Some viruses can look similar to tomato leaf roll, but if the symptoms appear suddenly, involve many of the plants in a field, and largely affects lower leaves, it is probably just physiological leaf roll.

Management: Reduce symptoms by maintaining consistent, adequate soil moisture (~1 inch per week during the growing season, which will also help with calcium uptake, reducing blossom end rot incidence). Do not prune heavily during hot, dry conditions or over-fertilize with nitrogen.

Catfacing

Tomatoes are considered “catfaced” if the blossom scar is enlarged or perforated. This can happen to both field and greenhouse tomatoes and is more common in heirloom cultivars and varieties with rounder and larger fruit. Often, the fruit becomes extremely misshapen, but fruit distortion is not necessary to classify it as catfaced. This disorder has not been extensively researched and is still not fully understood. Cold temperatures during flowering have been shown to increase incidence of catfacing, as have extreme fluctuations in night versus day temperatures. Damage from thrips to the side of the pistil of tomato flowers can also cause this disorder, and under some conditions, pruning and high nitrogen levels can increase catfacing incidence. Catfacing can increase the chances of fruit becoming infected via the rough blossom scar by black mold rot, a disease caused by several different fungi.

Management: Avoid excessive pruning and nitrogen fertilization. Avoid low greenhouse temperatures for both greenhouse tomatoes and transplants. Use cultivars that are less prone to catfacing. Remove catfaced fruit so they don’t drain plant nutrients. 

Stitching/Zippering

Stitching or zippering are terms for when a thin, brown, necrotic scar extends from the stem to the blossom end on fruit. The longitudinal scar has small transverse scars along it, making it resemble a zipper or seam. Fruit can have one or several scars. This disorder is purely cosmetic and does not affect the edibility of the fruit but may render fruit unmarketable. Zippering is caused by anthers (the pollen-producing flower part) fused to the ovary wall of newly forming fruit. This disorder occurs more frequently in cool weather.

Management: Plant cultivars that are less susceptible to stitching/zippering. Avoid low greenhouse temperatures.

Fruit Cracking

Fruit cracking can occur in several different patterns – radial cracks starting at the stem scar, concentric cracks circling the fruit shoulders, small cracks around the shoulders called “rain checking”. These cracks are caused by excessive water uptake by the plant during fruit development, when interior tissues expand faster than the inflexible skin. High temperatures can make fruits more susceptible to cracking, and cultivars with large fruit tend to be more susceptible. Opportunistic fungi and bacteria can enter the fruit through cracks and cause fruit rots.

Management: Provide even irrigation and plant cultivars with smaller fruit that are less susceptible to cracking.

L to R: radial cracking, concentric cracking, and rain check. Click on images to expand and see captions and photo credit.

Yellow Shoulder

Yellow shoulder is commonly caused by potassium (K) deficiency in tomatoes. Recent surveying by several New England state Extensions have shown that tomatoes, especially high tunnel tomatoes, have very high potassium requirements and crops tend to be deficient. Current nutrient recommendations advise New England growers to fertilize based on the potential yield of your crop (with indeterminate, disease-resistant cultivars planted early into heated tunnels expected to yield more than heirloom or determinate cultivars planted later). See the full recommendations in the high tunnel tomato section of the New England Vegetable Management Guide. One recommendation for K fertility in high tunnel tomatoes is to apply ¼ lb of K/1000 ft² through the drip every week for 10 weeks, using potassium sulfate fines. In both the field and high tunnels, the following factors can also lead to K deficiency in tomatoes: waterlogged and/or compacted soils, above-optimal nitrogen application rates, excessive application of cations that compete with potassium, and excessively large or dense canopies. Some cultivars, including those with green shoulders that lack the uniform ripening gene, are also more prone to developing yellow shoulder than others. High temperatures and sun can also cause this disorder, both by directly damaging fruit tissue and by inducing water stress that can limit the uptake of K.

Blotchy ripening, gray wall, and internal whitening

These three disorders are not well-understood and tend to be confused with each other. Blotchy ripening is characterized by yellow or orange discolored areas on tomato fruit surfaces. Tomatoes with gray wall have grayish-brown discolorations on the fruit wall and may also exhibit internal browning. Gray wall typically appears on green fruit before ripening. 'Gray wall' is the term used when the outer fruit walls turn brown or gray and collapse, compared to 'internal whitening', which refers to when the outer and inner fruit walls become white and corky. Factors that increase the severity of these disorders include cloudy weather, wet and cool conditions, high nitrogen, low potassium, and compacted soils. Good irrigation and nutrient management will reduce the risk of these disorders. 

Ripening disorders, including yellow shoulder, blotchy ripening, gray wall, and internal whitening, are most prevalent when air temperatures during mid- to late stages of fruit ripening are extreme (e.g., below 60°F and/or above 90°F) or highly variable, when humidity levels remain high, and/or when these conditions prevail and light levels are low. Unfortunately, these are not uncommon conditions in New England and are largely out of our control. Tomato mosaic virus can cause similar symptoms of uneven fruit ripening and should be ruled out as the underlying cause.

Planting tomatoes onto white plastic mulch and using shade cloth can help keep crops cooler and increase marketable yields. Research has shown that a 30% filtering shade cloth increases marketable yields by 20-50%, depending on the year. A 4 ft-wide shade cloth covering even a quarter of the crop canopy is sufficient to achieve this increase in yield, and the cloths may be used for many years.

--UMass Extension Vegetable Program

Alternaria leaf spot 

Alternaria leaf spot affects all cucurbit crops but is most common on cantaloupe. This disease is caused by the fungus Alternaria cucumerina. Like the Alternaria species that cause leaf spots in brassicas and early blight in nightshades, A. cucumerina causes a characteristic target-like spot. Usually, leaf spots are small and start out as tan flecks that enlarge and merge together. These larger spots (up to a half-inch) may exhibit the concentric rings common of all Alternaria fungi. This disease usually occurs in mid-season and can reduce late-season fruit production. Fruit lesions may also occur as sunken lesions with dark, olive-green, felt-like sporulation present in rings. Spores are spread from plant to plant via splashing rain or overhead irrigation, as well as by insects, workers, and equipment moving through the field. 

Septoria leaf spot

Septoria leaf spot is less common, occurring in cool summers or late fall. This disease is caused by the fungus Septoria cucurbitacearum, which causes small, almost white, round spots on leaves and superficial, raised tan bumps on fruit. Spores are spread from plant to plant via splashing rain or overhead irrigation, as well as by insects, workers, and equipment moving through the field.

 

Management

The impacts of these bacterial and fungal diseases can all be reduced through field sanitation and use of preventative pesticides, whether conventional or organic. 

• Start with quality seed, and/or fungicide treated seed. If saving your own seed, avoid collecting seed from fruit with any defects.

• Resistant or tolerant varieties of many cucurbit crops are available for most of these diseases. Meg McGrath of Cornell University has compiled extensive lists of disease-resistant varieties of vegetable crops.

• Use a 2-year rotation for cucurbit fields. All of these diseases survive on crop residue in the soil, which can persist for up to 2 years.

• Use drip irrigation to reduce the spread of bacteria and fungal spores by overhead irrigation.

• Don’t work in affected fields when foliage is wet, or work in unaffected sections first and infected sections last to avoid spreading disease to unaffected areas.

• Use fungicides or bactericides when you see the first leaf spots to slow the spread of disease. Submit a sample to the UMass Plant Diagnostic Lab so that you can choose an effective pesticide for the disease you have. Consult the cucumber, muskmelon, and watermelon or pumpkin, squash, and gourds disease sections of the New England Vegetable Management Guide for pesticide recommendations.

• Till under crop residues promptly after harvest is complete to encourage the quick breakdown of infected tissues.

--Written by Susan B. Scheufele, UMass Extension

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Events

Sprayer Calibration Workshop

When: Thursday, July 9, 2026, 4:30 – 7:30pm

Where: Gove Farm, Leominster, MA

Registration: Free, but please register in advance. Space is limited! Click here to register.

George Hamilton, of Hillside Meadows Ag Consulting and previously with University of New Hampshire Extension, will lead us through the calibration of a boom sprayer, teaching us along the way. We will experience how speed, pressure, nozzles, and boom height interact, and will then test to see if we’ve achieved the desired coverage. You’ll then use those concepts yourselves as you calibrate a backpack sprayer. This event is the first of our “From Tip to Tank: Pesticide Applicator Laboratory Series” events, funded by the Northeast Extension Risk Management Education Program.

Click here for full event description.

Questions? Contact Maria Gannett, mgannett[at]mass[dot]edu (mgannett[at]mass[dot]edu)  

All About Peppers – Twilight Meeting at Kitchen Garden Farm

When: Tuesday, July 21, 2026, 4-6 pm, followed by refreshments 

Where: Kitchen Garden Farm, 131 S. Silver Lane, Sunderland, MA 01375

Registration: Free! Please register in advance. Click here to register.

Kitchen Garden Farm is a 65-acre specialty vegetable operation and value added business in Sunderland, MA.  The farm grows a variety of crops to process into a line of hot sauces, salsas, pickles, and dried spices/herbs, including peppers, tomatoes, onions, cauliflower, celery, carrots, oregano, thyme, sage, as well as a diverse array of crops for niche regional and local wholesale markets.

This meeting will focus on their pepper production and some of their related challenges, including Phytophthora and pepper maggot, and work they're doing in collaboration with UMass Extension to try to improve management. The farmers will also share their experiences with learning about the risk management options available to their farm through crop insurance and the FSA's Non-Insured Disaster Assistance program (NAP). 

NEVBGA Twilight Meeting: Vegetable and Strawberry Variety Trials and Equipment Demo

When: Tuesday, August 18, 5:30-7pm

Where: UMass Crop Research Farm, South Deerfield, MA 01373

Registration: Free but please register in advance so we can order enough food! Click here to register.

Every year we conduct applied research trials using grant funding, collaborations with industry, and other government agencies, but an important source of funding for our team's research is the New England Vegetable and Berry Grower's Association. The NEV&BGA helps to fund research at land grant University's across New England to help find new crops, varieties, tools, methods and information growers need to continue producing the best crops. We are excited to invite you to the field to see the many variety trials we have planted this year, including:

• Seedless eggplant
• Spineless zucchini
• Supersweet corn
• Peanuts
• Strawberries
• Carrots

We will also have some equipment to demo including the Forigo stone burier, Tempus Ag automated irrigation system, Tilmor cultivating tractor, an abrasive weeder, and more!

BBQ dinner provided!

Questions? Contact Sue Scheufele, sscheufele[at]umass[dot]edu (sscheufele[at]umass[dot]edu), 413-477-3976

41st Massachusetts Tomato Contest

When: Thursday, August 20

Where: Boston Public Market

Please join MDAR and the New England Vegetable and Berry Growers Association for the 41st Massachusetts Tomato Contest! Tomatoes will be judged by a panel of experts on flavor, firmness/slicing quality, exterior color, and shape. Always a lively and fun event, the day is designed to increase awareness of locally grown produce.

Open to commercial farmers in Massachusetts, growers can bring tomatoes to the market between 8:45am and 10:45am on August 20 or drop their entries off with a registration form at one of the regional drop-off locations on Wednesday, August 19. Drop off locations include sites in South Deerfield, Southboro, North Easton and West Newbury. These tomatoes will be brought to Boston on Thursday.

Details, including drop off locations, contest criteria, and registration form here. *Be sure to include the registration form with all entries.

The 41st Tomato Contest is sponsored by the MDAR and New England Vegetable and Berry Growers Association, in cooperation with the Boston Public Market. Please consider participating to showcase one of the season’s most anticipated crops!

Questions? Contact Rose Arruda, rose[dot]arruda[at]mass[dot]gov (rose[dot]arruda[at]mass[dot]gov). 

Food Safety Farm Tour at Red Shirt Farm

When: Monday, August 31, 2026, 4-6 pm, followed by refreshments 

Where: Red Shirt Farm, 60 Williamstown Rd, Lanesborough, MA 01237

Registration: Free! Please register in advance. Click here to register.

Following good agricultural practices starts with understanding the potential hazards to fresh produce and assessing the risks they might pose on your farm. At this meeting Lisa McKeag, from UMass Extension, will talk about the basics of farm food safety—why we care about it and what to look for and think about when conducting a risk assessment, including common risks related to land, water, wildlife, hygiene, equipment, and harvest practices. Ben Comeau, from the MDAR Produce Safety Program will share insights from his own experiences as an inspector for the FSMA Produce Safety Rule as well as an auditor for Massachusetts voluntary certification program, Commonwealth Quality (CQP).

Presented by Berkshire Grown, MDAR, and UMass Extension.

Save the Dates!

• 2026 MA Fruit Growers' Association Summer Meeting: Wednesday, July 15, 9:30am-2:30pm, UMass Cold Spring Orchard, Belchertown, MA
• UMass Agronomy Farm Research Field Day: Wednesday, August 5, 9:30am-1pm, South Deerfield, MA
• Temporary Fence Installation & Maintenance: Thursday, September 17, 5-7pm, Heart Beets Farm, Berkley, MA

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Vegetable Notes. John Galvan, Maria Gannett, Genevieve Higgins, Lisa McKeag, Susan Scheufele, Alireza Shokoohi, and Hannah Whitehead, co-editors. All photos in this publication are credited to the UMass Extension Vegetable Program unless otherwise noted.

Where trade names or commercial products are used, no company or product endorsement is implied or intended. Always read the label before using any pesticide. The label is the legal document for product use. Disregard any information in this newsletter if it is in conflict with the label.

The University of Massachusetts Extension is an equal opportunity provider and employer, United States Department of Agriculture cooperating. Contact your local Extension office for information on disability accommodations. Contact the State Center Directors Office if you have concerns related to discrimination, 413-545-4800.