Vegetable Notes 2025 Vol. 37:20

There are many diseases that affect potato tubers, so ahead of your potato harvest this year, take a moment to familiarize yourself with the range of symptoms. Proper identification will help you decide which tubers will store well and which should be sold as tablestock, and will give you a better idea of which soil-borne diseases are present in your fields, improving your future crop rotations. To be sure of a diagnosis, samples can be submitted to the UMass Plant Diagnostic Lab. Most of these diseases (except for scabs, scurfs, and potato virus Y) get started on foliage and, if controlled there, can be prevented on tubers. See the New England Vegetable Management potato disease section for fungicide recommendations. 

Common scab (Bacterial: Streptomyces spp.) produces tan to dark brown, circular or irregular lesions, which are rough in texture. Scab may be superficial (russet scab), slightly raised (erumpent scab), or sunken (pitted scab). The type of lesion is dependent on potato cultivar, tuber maturity at infection, organic matter content of soil, strain of the pathogen, and the environment. Common scab is controlled or greatly suppressed at soil pH levels of 5.2 or lower, though a closely related but less common species of Streptomyces known as acid scab can survive down to 4.0. 

Maintaining moist soil conditions, especially during tuber initiation, can be an effective way to prevent scab infections, though is usually tricky to implement on the scale most potatoes are grown. 

Some varieties are more susceptible to scab than others, with red-skinned varieties generally being most sensitive and russets being most resistant. From Christopher Clark, USDA-ARS Vegetable Breeder, “Some recently released cultivars that are at least partially common scab resistant are Lamoka, Upstate Abundance, and Caribou, though none of these are highly scab resistant. In our very limited trials, Blazer, Canela, and Gold Rush Russet potatoes performed better for common scab resistance than some of the more commonly grown russets when challenged with the species of the pathogen that appears to be the most prevalent in New England. For red potatoes, Dark Red Norland performed the best for scab resistance in some of our limited trials among red potatoes, though it is still quite susceptible. Superior is a white potato that performs reasonably well for scab resistance.” 
For conventional growers, the fungicide quintozene (Blocker) seems to work quite well. 

Pumpkin & Winter Squash Harvest, Curing & Storage

It's almost time for pumpkin and winter squash harvest. Correct harvest timing, curing, and storage conditions can significantly affect eating quality, storage length and postharvest disease.

Harvest

Despite their tough appearance, squash and pumpkin fruit are easily damaged. It is important to avoid bruising or cutting the skin during harvest. Once the rind is bruised or punctured, decay organisms will invade the fruit and quickly break it down. Place fruit gently in containers and move bins on pallets. Use gloves to protect both the fruit and the workers. For some squash, especially butternut, stems can be removed to prevent them from puncturing adjacent fruit during harvest and storage. If stems are removed, allow the stem scars to heal before putting into storage (see Curing below). 

Harvest Timing for Winter Squash and Pie Pumpkins

For winter squash and pie pumpkins, harvest timing determines the flavor and texture of the fruit. As squash fruits grow, they accumulate starch, which is then converted into sugar in the field and during storage. The balance of starch (texture) and sugar (sweetness) in a squash determines the eating quality. Squash is mature when seeds are completely filled. If squash is harvested before it is mature, the fruit will use starch reserves from the flesh to fill the seeds, resulting in poor flesh quality. Immature squash will also not have enough starch to convert into sugar later on. 

Most squash varieties are mature and ready to harvest 50-55 days after fruit set, or days after pollination (DAP). In many varieties, this is many weeks after the fruit turns a marketable color, which can be misleading. Dr. Brent Loy, late researcher emeritus at the NH Ag Experiment Station, said that days to maturity listed in seed catalogs are often incorrect, especially for acorn squash; catalogs often state 70-76 days to maturity (from time of seeding) when in reality it’s more like 90-100 days to maturity. It’s not necessarily easy to keep track of fruit set, so there are some other indicators that squash is ready for harvest—see the end of this article for information specific to different squash types.

Harvest Timing for Halloween Pumpkins

Since the pumpkin market typically lasts from Labor Day to Halloween, pumpkins may need to be held for several weeks before they can be sold. One factor in deciding when to harvest is the condition of the vines. Intact foliage protects fruit from the sun, and when vines and foliage die down from powdery or downy mildew, fruit can get sunscald. Foliar diseases, especially powdery mildew, can also reduce the quality of pumpkin handles, leading to reduced marketability for jack-o-lantern pumpkins. As cooler fall weather approaches, the other major factor in deciding when to harvest is avoiding chilling injury. Chilling hours accumulate when squash or pumpkins are exposed to temperatures below 50°F in the field or in storage. Injury increases as temperature decreases and/or length of chilling time increases. This is particularly important for squash headed into long-term storage. 

There can be extra work involved in bringing fruit in early and finding good storage locations, especially for growers who normally have pick-your-own harvest. Ideally, pumpkins would be harvested as soon as crops are mature and stored under proper conditions. Proper curing and storage conditions are key for Halloween pumpkins in particular, because improper conditions can result in handles shrinking and shriveling, making the pumpkins unmarketable. If you need to hold fruit in the field for pick-your-own or any other reason, using a protectant fungicide (e.g. sulfur, oil, or chlorothalonil) along with one of the targeted powdery mildew products can help protect from black rot, powdery mildew, and other fungal fruit rots. Recommended materials can be found in our Managing Cucurbit Downy and Powdery Mildews article. For information on identifying and controlling fungal fruit rots of winter squash, see our Fruit Rots of Pumpkin and Winter Squash article. Insect pests may include squash bug nymphs and adults and striped cucumber beetles. Scout for insects feeding on the fruit and handles and control if damage is evident. See the Pumpkin, Squash, & Gourds insect control section of the New England Vegetable Management Guide for pesticide recommendations. 

Storage

Pumpkins and winter squash should be stored in a cool, dry, well-ventilated area. Store fruit at 50-60°F with 50-70% relative humidity. Chilling injury is possible at temperatures below 50°F, and long-term storage at temperatures above 60°F will result in weight loss due to increased respiration rates. Large fluctuations in temperature favor condensation on fruit within the bin, which encourages disease. Therefore, fruit temperature should be kept as close to the temperature of the air as possible to avoid condensation and fruit rot. Relative humidity above 70% provides a favorable environment for fungal and bacterial decay organisms, and relative humidity below 50% can cause dehydration and weight loss. In a greenhouse, temperature can be managed with ventilation on sunny days; heaters will be needed for storage into November and beyond. An inner curtain can reduce heat loss and cost. 

Storage life depends on the condition of the crop when it comes in and your ability to provide careful handling and a proper storage environment. All fruit placed in storage should be free of disease, decay, insects, and unhealed wounds. See the end of this article for maximum storage times for different types of squash. Fruit that has been exposed to chilling temperatures (below 50°F) will not store well and should be marketed first.

Few farms have the infrastructure to provide ideal postharvest conditions for all of their fall crops. Fortunately, finding a method that is ‘good enough’ often does the job. Even if it is difficult to provide the ideal conditions, storage in a shady, dry location, with fruit off the ground or the floor, is preferable to leaving fruit out in the field.

Additional information:

• Eating Quality in Winter Squash and Edible Pumpkins
• Maximizing Yield and Eating Quality in Winter Squash - A Grower’s Paradox
• Managing Winter Squash for Fruit Quality and Storage

--Written by G. Higgins and R. Hazzard, compiled in 2018 from resources by Brent Loy, late researcher emeritus, New Hampshire Agricultural Experiment Station, and professor emeritus of genetics, UNH.

Organic High Tunnel Growers: Sign Up to Participate in HT Cover Crop Planting Trial – Receive Free Cover Crop Seed

The University of Minnesota and University of New Hampshire High Tunnel Cover Crops Trial is recruiting a large number of organic high tunnel growers to receive cover crop seed and participate in cover crop planting during the next calendar year. They are currently enrolling farmers for the fall 2025, spring 2026, and summer 2026 timeslots. The project aims to enable organic high tunnel growers to reduce their dependence on purchased composts and manures by using nitrogen-fixing legume cover crops. Farmers can select between two levels of participation and compensation, depending on the amount of time and effort they are willing to commit. You can read the full trial instructions, detailed species and timing menu, and farmer expectations for each level here.

The team held an informational webinar about the project on August 18th. You can view a recording or contact their team at hightunnel-cc[at]umn[dot]edu (hightunnel-cc[at]umn[dot]edu) with any questions.

Participating farmers will receive seed of "best bet" legume cover crops for your chosen timeslot, as well as a free soil test. To learn more about participating in the trial or to sign up, please fill out the interest form.

MDAR Endangered Species Act Notice

In April of 2022, the Environmental Protection Agency (“EPA”) released the Endangered Species Workplan which describes the strategies and actions to comply with the Endangered Species Act (“ESA”) when registering pesticides. Since then, EPA has begun implementing these strategies and actions to make sure pesticide use does not jeopardize federally listed and endangered plants and animals. Additional mitigation measures for pesticides may be needed to protect these endangered species. This includes items such as using websites or calculators to determine additional steps that a pesticide applicator may have to follow to use a pesticide. Additionally, these measures may impact whether you can use a product during a particular time of year.

When new products are registered, they will likely contain ESA-related language on the labels, while currently registered products will have such language added when these products go through their registration review process. To prepare for these changes, pesticide applicators should be reviewing their labels on a regular basis to become aware of when a label has changed and seek 
opportunities to attend trainings that include information about the ESA label language.

Through its stakeholders and partners, MDAR plans to provide education/outreach opportunities to the agricultural community which will provide more detail and guidance as to how to follow the new label language and use the tools that EPA has developed. In the meantime, you can find more information about this topic at the links below:

• ESA Workplan: https://www.epa.gov/endangered-species/epas-workplan-and-progress-toward-better-protections-endangered-species
• ESA Toolbox: https://www.epa.gov/endangered-species/pesticides-and-endangered-species-educational-resources-toolbox
• Bulletins Live Two: https://www.epa.gov/endangered-species/bulletins-live-two-view-bulletins
• Mitigation Menu: https://www.epa.gov/pesticides/mitigation-menu
• Webinar on September 16th: register here!

EPA Webinar on Mitigation Measures to Protect Endangered Species from Pesticides

When: Tuesday, September 16, 2025 from 2pm to 3:30 pm

Where: online

Registration: Register here

The U.S. Environmental Protection Agency (EPA) will hold a public webinar to provide information on the ecological runoff/erosion and spray drift mitigation measures that can be used to protect endangered species from pesticides. These measures are part of EPA’s online menu of mitigation measures pesticide users can choose from depending on their crop, region, agronomic practices, and the individual field to protect endangered species. The mitigation menu approach is intended to improve flexibility for pesticide users by providing options that work best for their situation, while still achieving an appropriate level of mitigation.

The purpose of the webinar is to help users better understand and use the mitigation menu webpage.  The webinar will include: 

• An overview of the runoff/erosion and spray drift mitigation measures and how pesticide users and growers can evaluate their fields for these mitigation measures.
• An explanation of how to navigate the mitigation menu webpage and available resources.
• A demonstration of the runoff/erosion mitigation calculator and the spray drift calculator, available on the mitigation menu webpage.

Cut Flower Twilight Meeting at Full Well Farm

When: September 18, 4-6pm

Where: Full Well Farm, 313 East Road, Adams, MA 01220

Registration: Event is free, please register in advance here.

Join us in the Berkshires! Farmer Laura Tupper will lead a farm tour with a focus on cut flower production. She will also discuss the paper pot transplanter that she uses to grow sunflowers. Extension Educator Hannah Whitehead will talk about a UMass project to track labor and costs associated with sunflower production, and UMass summer intern Athena Vasilopoulos will share their insect collection and talk about scouting for beneficial and pest insects. A light dinner will be provided. 

Save the Date! Local Flower Collectives

When: November 6, 11-12pm

Where: Virtual

Registration: Free, but registration is required.

Join us to learn more about cut flower collectives! Speakers include representatives from the Maine and Connecticut Flower Collectives.