Implementing Sustainable Management of Muskmelon Diseases, Weeds, and Insect Pests in Partnership with Iowa Growers

View the project final report

• 2003 annual report
• 2004 annual report
• 2005 annual report

Commodities

• Fruits: melons

Practices

• Crop Production: cover crops
• Education and Training: decision support system, demonstration, extension, on-farm/ranch research
• Farm Business Management: budgets/cost and returns
• Pest Management: biorational pesticides, chemical control, cultural control, disease vectors, field monitoring/scouting, integrated pest management, mulches - killed, physical control, row covers (for pests), trap crops, traps, weather monitoring, weed ecology

The goal of our research and outreach project was to enhance sustainability of muskmelon disease, weed, and insect pest management while reducing pesticide inputs. Muskmelon, a key high value crop, relies heavily on costly synthetic pesticides and fertilizers that endanger grower and consumer health, kill non-target organisms, and pollute the environment.

Our research clearly demonstrated the effectiveness of row covers in reducing insecticide use, decreasing the incidence of bacterial wilt, and increasing muskmelon yields. This outcome provides muskmelon growers with a practical alternative for control of bacterial wilt that is likely to improve profitability and reduce insecticide use compared to conventional management practices. In addition, cooperating commercial muskmelon growers successfully utilized row covers in their own operations. These results are published in a peer-reviewed journal and in extension and trade-journal publications. We also presented these results to growers at field days and workshops.

Using the Melcast warning system with input weather data from either on-site weather sensors or commercially available site-specific estimates reduced fungicide sprays compared to conventional, calendar-based spray program and provided equivalent control of anthracnose, caused by Colletotrichum orbiculare. These findings benefit growers by providing a convenient, reliable alternative to using on-site weather sensors in implementing a disease-warning system. Weather sensors and dataloggers are expensive, require regular maintenance, and demand time to download weather data. Growers can obtain site-specific weather estimates far more easily, via e-mail or the Web, than making on-farm measurements; our work shows that these data will reduce fungicide sprays while providing good disease control.

Our weather modeling work showed the feasibility of using near-field weather sensors as another alternative to within-field sensors that are subject to damage from tillage and other agronomic activities. The near-field sensors provide another option for growers to make implementation of disease-warning systems more convenient and practical. Three publications in peer-reviewed research journals resulted from this effort.

We experienced problems with current strategies to use trap crops to reduce the incidence of bacterial wilt in muskmelons by reducing cucumber beetle feeding. We found that trap crops commonly used may not be the most effective species and cultivars, so we devised a Year 3 trial to determine which species and cultivars might work better. Our results point to several cucurbit varieties that have good potential to serve as effective, season-long trap crops. Future trials should deploy these trap crops to test their ability to reduce bacterial wilt.

Our experiments with using a hairy vetch-rye cover crop to control weeds in muskmelon gave inconsistent results, with weeds sometimes becoming a major problem in these trials. An unanticipated disadvantage of this strategy in Iowa is that muskmelons cannot be planted into the cover crop until the vetch flowers; this occurs in mid-June in Iowa, which means that melons will be harvested from these plots too late (e.g., late August) to fetch adequately profitable prices at local markets or supermarkets. We concluded that the hairy vetch/rye strategy may be better suited to warmer climates than Iowa, and that further experimentation is needed to develop an optimal method for pushing the cover crop down to soil level before transplanting melons.

Introduction:

Muskmelons are among the top 5 vegetable crops in the North Central Region in number of growers (2,000), acreage (8,000 acres), and farm gate value ($25 million) (NASS, 2001). As a high-value annual crop, muskmelons offer rapid diversification and enhanced cash flow for grain and livestock operations seeking to diversify, as well as for conventional and organic vegetable growers.

Muskmelons in the North Central Region are heavily dependent on synthetic chemical inputs. Current Cooperative Extension guides recommend up to 15 fungicide, insecticide, herbicide, and fertilizer applications per season (Foster et al., 2001). This chemical intensive regime is not sustainable because it poses a significant risk of pesticide injury to growers who apply the chemicals, kills many vulnerable non-target organisms in and near fields, and can endanger the general population through residues on melons and pollution of drinking water sources.

Until now, alternatives to reliance on synthetic chemical inputs have been unavailable. Genetic resistance to the most important insect pests (cucumber beetles) and most of the major diseases (including anthracnose, gummy stem blight, Alternaria leaf blight, and bacterial wilt) is absent in commercial muskmelon cultivars (Foster et al., 2001). Total yield losses from these pests and diseases can exceed 70% for North Central Region growers (Latin, 1993). Traditional cultural techniques like crop rotation, while helpful, are insufficient to reduce reliance on synthetic pesticides. Monitoring of cucumber beetles as a management decision aid is difficult on muskmelons because the action threshold is extremely low (one beetle per plant) (Foster et al., 2001). Traditional clean-cultivation practices for weed control are time-consuming, energy intensive, and worsen wind and water erosion of topsoil.

Economic pressures have made pesticide intensive muskmelon culture even more untenable. Profitability of using synthetic pesticides in agriculture has declined steadily, and is now only 1/3 the level of 1970 (Carter, 2001). Steadily increasing national and global competition has squeezed profits and forced muskmelon growers to seek new ways to control costs of off-farm inputs, including pesticides.

OBJECTIVE 1: Suppress bacterial wilt and cucumber beetle feeding injury on muskmelons as effectively as conventional insecticide-based method by integrating mass trapping, trap crops, row covers, neem, and kaolin clay.

OBJECTIVE 2: Alternative strategies against the fungal disease complex of anthracnose, gummy stem blight, and Alternaria leaf blight.

OBJECTIVE 3: Evaluate the ability of a hairy vetch-rye cover crop to suppress weeds, reduce applications of conventional herbicides, and add nitrogen to soils.

OBJECTIVE 4: Combine the most promising component strategies from Objectives 1-3 into systems-level strategies that integrate weed, insect, and disease management.

OBJECTIVE 5: Document economic costs and benefits of these new management tactics in comparison to conventional practices.

OBJECTIVE 6: Transfer the project’s findings to muskmelon growers through on-farm demonstration trials, a WWW site, quarterly newsletter articles, presentations at regional grower meetings, annual field days, press releases, and an extension bulletin.