IPM Impacts
Curious about the work we do about the Colorado Center for Sustainable Pest Management? Our impact statements provide a quick and easy way to understand the significance of our efforts. These concise summaries detail our research projects by first describing the problem, then outlining the research or activities conducted to address it, and finally highlighting the impacts and value of this work to the public.
Alfalfa mosaic virus in Colorado chile pepper production
Issue
Chile peppers are a key specialty crop in Colorado, with 234 farms generating more than $2 million in value from 548 harvested acres in 2022. Since 2019, alfalfa mosaic virus has drastically reduced chile pepper yield and quality in Colorado, causing blotchy, misshapen, stunted pepper fruits and damaged plants. In severe cases, peppers are destroyed and portions or whole crops are lost, resulting in lost income for producers and reduced availability of locally grown chile peppers for Coloradans. The virus is most commonly transmitted by aphids who carry the disease and spread it to chile peppers as they pass through the fields. (Aphids don’t feed on chile pepper plants but do probe them as they look for palatable food sources.) Because the insects don’t linger in pepper fields, chemical pesticides are ineffective and integrated management tactics are the key to decreasing the impact of the disease.
Research
On-farm research projects were conducted with Colorado chile pepper producers from 2022 to 2024. Factors influencing alfalfa mosaic virus in chile peppers were evaluated, including 1) screening for resistant varieties, 2) modifying planting dates, and 3) proximity to alfalfa fields.
- Beginning with extensive greenhouse experiments, more than 30 varieties of chile peppers were screened and cultivars with strong tolerance to the virus were identified. Resistance to alfalfa mosaic virus was validated through on-farm trials.
- Early planting, while exposing peppers to the highest aphid densities and increasing severity of the virus, also resulted in higher yields despite high disease incidence.
- Preliminary results indicate that the closer peppers are grown to alfalfa, the greater the likelihood of high disease incidence and severity. Aphids flee alfalfa fields after hay cuttings and move to and through nearby fields.
Impact
- Producers can now select resistant varieties and optimize early planting times to reduce their losses from alfalfa mosaic virus and achieve higher yields and greater income.
- By understanding aphids’ transitory behavior, growers can avoid ineffective insecticide applications, reducing their expenses and benefiting the environment.
- Growers can strategically select where to plant peppers, avoiding nearby alfalfa fields entirely or choosing specific pepper varieties to plant in fields near or far from alfalfa.
- Pepper breeders can use the identification of alfalfa mosaic virus-resistant pepper varieties to develop and promote resistant seeds.
Public value statement
Reducing alfalfa mosaic virus in Colorado chile peppers safeguards one of the state’s most unique and valuable specialty crops. These efforts bolster Colorado’s agricultural economy, strengthen rural communities, and enhance the competitiveness of Colorado chile peppers on a national and global scale.
Protecting Colorado quinoa from a stem-boring fly
Issue
Quinoa is a climate-resilient, water-efficient superfood grown in Colorado and more than 3,000 acres were cultivated in 2021. However, a stem-boring fly discovered that year proved devastating to the crop and, by 2024, only 100 acres remained in cultivation. All Colorado quinoa producers have suffered catastrophic yield losses, forcing most to abandon quinoa cultivation altogether. Fly larvae destroy the plant’s stems from within, where they are protected from beneficial insects and insecticide treatments. With little other knowledge about the fly’s biology, farmers are left without effective management strategies, jeopardizing the crop, their livelihoods, and Colorado’s agricultural future.
Research
Beginning in 2021, on-farm research was conducted with Colorado quinoa growers to study the fly’s life history traits and develop integrated management strategies for its suppression. These ongoing efforts focus on 1) investigating the timing and patterns of fly activity in fields, 2) identifying other plants the fly uses as hosts for its larvae, 3) screening quinoa varieties for resistance, and 4) evaluating the efficacy of both conventional insecticides and biological controls.
- In tracking patterns of fly abundance over three years, researchers developed models to predict the timing of adult activity so growers can adjust planting and management tactics accordingly. Significantly lower numbers of flies in recent years are strongly correlated with lower overall acreage of quinoa, suggesting that areawide rotation of the crop may be key to fly management.
- Researchers discovered several common weeds – including lambsquarters, wild sunflower, and Palmer amaranth – can serve as host plants for the fly.
- Screening of quinoa varieties provided by commercial and university breeding programs revealed weak resistance to the fly. Further variety screening is underway.
- Treating quinoa seeds with a fungus that kills insects, Beauveria bassiana, shows promise as a biological management strategy. No commercial insecticides have been effective.
Impact
- Producers now know to manage weeds that are alternate hosts of the fly in and near quinoa fields to reduce fly populations.
- Producers understand that few quinoa varieties are resistant to the fly.
- Understanding the fly’s behavior and the inefficacy of insecticides, producers will avoid unnecessary applications, cutting their costs and reducing environmental impact.
- Producers recognize that further research will be necessary to develop effective integrated management strategies to control the quinoa stem fly.
Public value statement
Learning to manage the stem-boring fly is vital to Colorado’s emerging quinoa industry. Protecting this drought-resilient, nutrient-rich crop will enhance local food security and support climate-friendly sustainable agriculture. Strengthening Colorado quinoa production not only bolsters our economy but also reinforces Colorado’s commitment to health, wellness, and sustainability, solidifying our reputation as a leader in cultivating healthier futures.
Colorado wheat
Issue
Wheat is Colorado’s most extensively planted crop, with a value of $522 million in 2023 and 1.84 million acres harvested in 2024. Insect pests and pathogens present two of the greatest threats to crop profitability. Wheat stem sawfly larvae caused an estimated $41 million in losses in 2022 by boring into stems, weakening plants, and complicating harvests. Larvae overwinter in remaining stubble of cut wheat stems, slightly below soil level, making them difficult to control with insecticides. Management strategies include planting resistant varieties, crop rotation, and early harvesting. Disease-causing pathogens lead to yellow streaking, leaf curling, stunted growth, and reduced grain production – sometimes destroying entire fields. Chemical management is challenging, so strategies focus on planting resistant varieties, removing residual wheat, and strategic timing of planting. Integrated management approaches to these pests are necessary, as no single strategy is effective for both insects and pathogens.
Research
Colorado State University is conducting groundbreaking research to tackle insect and pathogen pests affecting Colorado wheat. The most recent work includes 1) screening for varieties resistant to insects and diseases, 2) surveying insects and pathogens, and developing tools to predict insect abundance.
- In 2024, 90 new wheat breeding lines possessing resistance to wheat stem sawfly were evaluated for grain yield, disease and pest resistance, and milling and baking quality across multiple environments in Colorado. Two varieties show resistance against two of the most destructive wheat pathogens. Overall, 20 breeding lines were selected for further testing in 2025.
- Wheat stem sawfly range and infestation were monitored across more than 100 field locations in Eastern Colorado and Western Kansas from 2022 to 2024. A degree-day model, based on 13 years of population data, is being used to predict adult sawfly emergence and peak abundance.
Impact
- The identification of promising resistant varieties will continue to strengthen wheat production, allowing for effective means to withstand attacks from the crop’s key insect pests and pathogens. These breeding lines have the potential to become new commercially available varieties and increase profitability for Colorado wheat growers.
- Growers can use the degree-day model to more effectively time their management practices, allowing for more targeted and efficient pest management measures.
Public value statement
Minimizing the impact of insect pests and pathogens on wheat is crucial, as wheat is Colorado’s most extensively planted and one of its most valuable crops. A robust wheat industry bolsters Colorado’s agricultural economy and supports rural communities, enhancing the competitiveness of Colorado wheat at both national and global levels, ultimately ensuring sustained economic growth and food security.
Get Started Today
Contact the Department of Agricultural Biology
Plant Sciences C 129
Campus Delivery 1177
Colorado State University
Fort Collins, CO 80523-1177
(970) 491-5261
cas_agbiomain@mail.colostate.edu