Oct 21, 2025

Mesotunnels and muskmelons: Optimizing row covers for sustainable agriculture

Organic and sustainable specialty crop growers face a unique balancing act of producing high-quality crops while preserving the health of the environment for seasons to come. 

However, every growing season brings an army of challenges: insect pests, diseases, weeds, sunburn, frost, mammals and increasingly unpredictable weather. 

In organic systems where the toolbox is more limited, tackling these stressors can be especially tough. Many growers rely on OMRI-listed pesticides, but they’re not always up to the task. Repeated applications can be costly, labor-intensive and environmentally taxing, leading to issues like copper accumulation in the soil. Inconsistent product performance against important pests and diseases increases the risk of crop loss and chips away at already narrow profit margins. 

Row cover aid

That’s why physical tools like row covers have become staples in organic integrated pest management (IPM). In a 2022 survey of 377 organic specialty crop growers across the Midwest, Southeast and Northeast, insect pests ranked as the top production challenge, followed by heavy rainfall, disease and weeds.1 More than 60% of growers reported using row covers not just for pest control but also to soften the blow of extreme weather and reduce the reliance on pesticides and other chemicals.

Not all row covers are created equal, especially given the diversity of crops, rotations and infrastructure, particularly on organic farms. Some growers produce more than a dozen species a season. While many growers are familiar with low and high tunnels, each comes with its own set of benefits and trade-offs. 

In recent years, a middle-ground option has emerged: mesotunnels. As the name suggests, “meso” means “middle,” and that’s exactly where these tunnels fall in size and structure. 

Standing 36 to 48 inches tall, mesotunnels are taller than low tunnels but shorter than high tunnels, offering extended season-long protection. They are built with steel conduit hoops and covered with a fine nylon mesh, such as ExcludeNet or ProtekNet, that allow light, air and sprays, and rainfall to reach the crop while excluding insect pests. The mesh can be reused for multiple seasons, especially if stored properly during the off-season. 

Flexibility

Mesotunnels are not a one-size-fits-all solution, but they show promise as a flexible tool in organic production, especially in specialty crops. At Cornell and partner institutions in southern and midwestern states, we have tested them in cucurbit systems where insect-vectored diseases are a recurring issue. 

Pests like striped cucumber beetles and squash bugs don’t just cause damage by feeding on crops — they also spread bacterial pathogens that can cause plant death. For example, bacterial wilt is caused by the bacterium Erwinia tracheiphila and spread by cucumber beetles. Cucurbit yellow vine disease is caused by the bacterium Serratia marcescens, which is spread by squash bugs. Losses associated with these insect pests can really add up for smaller-scale organic farmers.

A key question surrounding the use of exclusion netting and row covers is how to balance pollination with the benefits of excluding insect pests. Trials in New York, Iowa and Kentucky tested different approaches. One method involved clipping the tunnel ends open during flowering, or anthesis, which allowed pollinators to access the crop and achieve fruit set. 

After pollination was complete, the netting was closed again and secured with sandbags. In contrast, completely removing the tunnels during flowering led to a surge in pest populations. When the netting was reapplied, many insect pests remained inside for the rest of the season, which eliminated the protective benefits of the system. The clipped-end approach provided a more balanced solution, supporting pollination while providing pest exclusion.

Bee aid

Pollinating insects, including honeybees and native squash bees, were able to navigate into the tunnels through the open ends, while pest insects were less successful. After the ends were closed, very few pests were found inside compared to the full removal treatment, which had pest numbers like plots that were not covered.

Mesotunnels are not a silver bullet, but they are a valuable tool in the organic IPM toolbox. Like any system, they work best when used alongside practices like pest scouting, crop rotation and cultural controls. 

Our initial trials began with acorn squash, but growers noted that for the labor involved, especially early in the season with tunnel establishment, the protected crop needed to be higher value. We listened and shifted our focus to muskmelon, where full-season protection offers a better return. 

To help maximize return on investment, we optimized the materials and transferred the same mesotunnel structures onto a fall cole crop, such as cabbage, to extend their utility beyond a single specialty crop per year. 

Hands-off help

While the setup can be labor-intensive at the start, once in place, mesotunnels allow for a relatively hands-off approach to pest and disease protection throughout the growing season.

To optimize this system further, we are exploring complementary practices that may improve outcomes under mesotunnels. This includes cultivar selection, cover cropping and weed management strategies that could influence key variables like yield, disease pressure, insect populations, soil health and microclimate. 

Though mesotunnels may not be the best fit for large-scale conventional operations, they hold real promise for small to mid-sized farms, especially those facing increasing pest populations that are also looking to reduce both chemical and plastic inputs. As food production systems continue to evolve, mesotunnels offer a way to balance protection, productivity and sustainability to support the future of resilient, diversified farming.

Reference: Cheng, N., Zhang, W., & Gleason, M.L. (2025). Controlling Pests and Diseases using mesotunnels: Understanding organic cucurbit crop growers’ preferences and choices. SSRN Electronic Journal. doi:10.2139/ssrn.5212644.

BIOS

Kaitlin Diggins and Sarah Pethybridge are located at Cornell AgriTech in Plant Pathology and Plant-Microbe Biology at Cornell University. 

Sarah Pethybridge is a research and extension pathologist working on vegetable diseases at Cornell AgriTech in Plant Pathology and Plant-Microbe Biology at Cornell University. The goal of her program is to conduct novel studies on pathogens and diseases affecting vegetables in New York to underpin profitability and sustainability of the industry.

Kaitlin Diggins is a Ph.D. candidate whose dissertation research focuses on the development of integrated pest management programs in mesotunnel production systems, with a particular focus on increasing climate-resilience and plant health in sustainable agriculture and certified organic specialty crops.