Small farms: On the front lines of emerging agricultural pests

By Emily Kraus, Ph.D.

In the San Joaquin Valley of California is a large and diverse community of agricultural producers. Within this community are growers who own or rent small parcels to do their farming and generate less than $350,000 a year. These ″small farmers″ include Hmong, Hispanic, and African American growers who have historically been underserved and undervalued. Their farms are diverse, including southeast Asian vegetables, solanaceous crops like tomatoes, and perennial crops like jujube. The nature of these farms often present unique hardships in pest management, but these growers don’t shy away from a challenge. In fact, they are at the forefront of noticing when something isn’t ″normal,″ and often they are the first in the area to share observations of invasive and emerging pests.

For extension professionals, trustworthy relationships with growers are critical. An entomologist in the San Joaquin Valley of California explains how relationships with small-farm producers—a diverse, often underserved community—have been a key factor in early detection and response to new and emerging insect pests. Here, a group of small-farm producers meet with members of the University of California Cooperative Extension Fresno and Madera County Small Farms Team in a moringa (Moringa oleifera) field. (Photo by Emily Kraus)

Connecting to Growers

Small-farm producers in the San Joaquin  Valley grow a variety of Asian specialty  vegetables. (Photo by Emily Kraus)

The University of California Agriculture and Natural Resources (UCANR) includes the University of California Cooperative Extension (UCCE) and the Fresno and Madera County Small Farms Team. This is a group of research and extension professionals who serve the local small farms. The team has strong relationships with growers stemming from direct support of members of the community who work with UCCE. For example, Michael Yang has worked with UCCE for 30 years and is himself a respected elder in the Hmong community. Through his connections, other UCCE staff members have been able to meet growers and earn their trust.

None of the team’s present or future work would be possible without such connections to the growers. New extension professionals may find that developing these relationships looks different based on their specific roles. For example, an existing program with team members who have connections to the community can more easily make introductions and bring a new hire into the fold. If an extension professional were to start a new program, establishing connections and relationships will take more time. Reaching out to organizations that have worked with small-farm growers, connecting to respected members of the community, and using connections through the other extension professionals in your own organization can help.

It may take several years to develop a base of knowledge in the specific areas you have been assigned. Many who enter the small farms world do not have experience in crops such as opo, bitter melon, or loofa, but this knowledge can be gained over time while relationships are being built. In fact, asking growers about their growing processes and their opinions can be great conversation starters! Through these interactions, new professionals can build mutual respect and trust.

It is on this foundation of trust that we’ve built with Fresno’s small-farm growers that UCCE Small Farms Team can collaboratively tackle farming challenges. These interactions include advising on extreme weather, soil and water conservation, and sustainable agriculture techniques such as finding pest management solutions.

Michael Yang is a community education specialist at the University of California Cooperative Extension. He is deeply connected to Hmong growers in Fresno County and often introduces new team members to growers, making networking with this unique group possible. (Photo by Michael Yang)

Emerging Pests on Small Farms

In recent years, several pests that had previously been absent began to show up in crops on Fresno small farms. In each of these cases, the growers brought the issue to the attention of the Small Farms Team. In July 2024, for instance, a grower called the team about a problem with his sunchoke, also called Jerusalem artichoke (Helianthus tuberosus). Across his field plants were dying from the top down and drying out. As the team’s entomologist, I went for a visit to the farm and noted frass and symptoms of larvae boring in the plants. I collected the larvae and reared them out until they pupated into adult moths. Then, with the help of Gene Hannon at the Fresno California Department of Agriculture, we confirmed the pests as the sunflower bud moths (Suleima helianthana). Due to the larvae’s behavior of boring into the stems, they are protected from external pesticide applications. Additionally, California has some of the strictest regulations on neonicotinoids, and the crop is a sunflower, which pollinators love, so systemics are not an option. This calls for investigation next season on planting dates, pre-bloom management, and efforts to find novel solutions to this new plant-insect interaction.

Sunflower bud moths (Suleima helianthana) have been noted as a pest in states with commercial sunflower production. Summer 2024 was the first time it has been noted on sunchoke in the San Joaquin Valley. (Photo by Emily Kraus)

Another new pest in the area, and perhaps the one of greatest concern, is the Mexican rice borer (Eoreuma loftini). This insect feeds on rice, sugarcane, lemongrass, and sorghum as well as many non-crop hosts. It was noted in small-farm lemongrass at the end of 2023, though we expect it’s been here longer. Since its discovery, it has been confirmed in lemongrass and rice, and adults have been collected in sugarcane and sorghum fields in the area. An effort is being made to track its expansion through the state as well as to work with IR-4 on testing insecticides. Currently no insecticides are labeled for lemongrass that would be effective against the pest. Like the sunflower bud moth, this insect is a borer as a larva and therefore difficult to manage with contact insecticides. However, lemongrass does not flower in California, meaning more insecticide options will be available, with less potential harm to pollinators.

When the larvae of Mexican rice borer (Eoreuma loftini) feed inside rice stems (left), it causes this damage known as whiteheads. Each of the panicles affected will have no grain and represent a total yield loss per panicle. In lemongrass (right), the larvae cause brown lesions and fill the stem with frass, ultimately causing the stems to rot. These stems are not suitable for sale in farmers markets and represent yield loss. (Rice photo by Michael Yang; lemongrass photo by Emily Kraus)

In a final example of emerging insect pests, growers found increasing amounts of discoloration on leaves of moringa (Moringa oleifera) in 2021. They thought there was a pest problem and brought it to the attention of the team. The pest was identified by morphology alone as bean thrips (Caliothrips fasciatus). Like most specialty crops, few chemical treatments are available for growers. Additionally, moringa is often purchased by clientele who prefer organic products. The Small Farms Team is looking into integrated pest management solutions at the UCANR Kearny Agricultural Research and Extension Station.

Insects are not the only pest that small farms are encountering. In 2024 growers noticed strange symptoms of a pest in long bean (Vigna unguiculata ssp. sesquipedalis). The Small Farms Team sent samples to the UC Davis pathology lab, which isolated a fungal pathogen Fusarium solani. This was troublesome, as long bean is already noted to be under pest pressure from aphid and nematode populations in the area. Some lines of cowpea are resistant to all three pests, and varietal resistance trials are underway. In this case, there may be hope for reduced pest damage in the future without the use of chemical applications.

Conclusion

Growers on small farms in the San Joaquin Valley are intelligent and observant. They work collaboratively with the UCCE Small Farms Team to find solutions to new and daunting problems. This relationship works so well due to the time the UCCE team has put into building trust within the community. Hosting workshops and field days, doing one-on-one site visits, and circling back to check on growers reinforces these relationships. It is time consuming to help individual farmers troubleshoot. It’s also worth it. When a grower tells others in the community how you have supported them, it encourages them to show up to events and to reach out when they encounter challenges. When coming into a new extension role, it is imperative to connect with individuals and organizations that have existing relationships with growers. They can make introductions so that you can spend time on the ground with growers and show them through your actions that you can be trusted.

Farmers tend to notice pest problems before researchers do, and afterwards the Small Farms Team can use its resources to identify pests and fund research projects to determine solutions. However, specialty crops and small farms face many challenges that commercial growers do not. It is challenging to acquire funding for projects that support fewer growers in overall numbers, even though these farms represent these farmers’ cultures and livelihoods. Additionally, there is minimal acknowledgment for this type of grower on the federal level, which means the Small Farms Team must help provide them with a voice to the industry and technical assistance. The UCANR Small Farms Team in Fresno will continue to seek funding and support to investigate these emerging pest issues in hopes of uplifting this outstanding community of growers.

Read the original article at Entomology Today.