Implementing Sustainable Management of Muskmelon Diseases, Weeds, and Insect Pests in Partnership with Iowa Growers
The goal of multidisciplinary research and outreach project is to enhance sustainability of muskmelon disease, weed, and insect pest management. Muskmelon, a key high value crop in the Midwest, relies heavily on costly synthetic pesticides and fertilizers that endanger grower and consumer health, kill non-target organisms, and pollute the environment. We will investigate innovative tactics that can reduce or replace these toxic inputs.
Field trials in Iowa will use mass trapping augmented by trap crops, row covers, neem, and kaolin clay to deter bacterial wilt transmission and feeding injury by cucumber beetles. Another field experiment will evaluate control of anthracnose, gummy stem blight, and Alternaria leaf blight by the biological control bacterium Bacillus subtilis, the organically-approved fungicide potassium bicarbonate, and the Melcast disease warning system, which allows growers to time fungicide sprays efficiently. We will also assess suitability of a hairy vetch-winter rye mulch to replace synthetic herbicides and fertilizers in managing weeds and nitrogen fertility. By combining Year 1 results with findings of our on-going muskmelon research at Iowa State University, we will have enough data to integrate the most promising of these new strategies into systems-level field trials in year two, and to determine input costs, profits, and risks associated with all strategies. Growers throughout IOWA will learn about the new methods through 6 on-farm trials per year, an annual field day, a World Wide Web site, newsletter articles, 4 press releases, and an Extension bulletin.
Iowa muskmelon growers are full partners in the project from start to finish. Growers have provided feedback on the proposal, and there will be growers included in on-farm cooperative trials.
Short-and long-term outcomes include identifying practical management tactics that reduce reliance on both pesticides at risk under FQPA and nitrogen fertilizer, participation of growers in on-farm trials, and adoption of one or more of the new methods. Long-term outcomes include higher farm profits, reduced pesticide-related health risks for muskmelon growers and consumers, reduced hazard of groundwater and surface water pollution, and healthier and more stable rural communities.
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.
These experiments were completed in 2003 and 2004. However, an additional experiment was completed to evaluate which cucurbit variety was best suited for use as a trap crop (attractive to beetles yet not susceptible to wilt). The experiment included 50 varieties of cucurbits. Squash types included acorn (4 varieties), buttercup (7 varieties), butternut (3 varieties) delicate (5 varieties), hubbard (3 varieties), spaghetti, Turks turban, green zucchini (7 varieties), yellow zucchini, yellow straightneck (2 varieties), yellow crookneck (2 varieties), patty pan (2 varieties), pumpkins (5 varieties), cucumber (3 varieties), watermelon (3 varieties), muskmelon and ornamental gourds. Numbers of stripped and spotted cucumber beetles were tracked weekly. The survival of the cucurbit plants were evaluated at 6 weeks and 10 weeks. Four replicates of the varieties were planted in a single plot at the Horticulture Research and Demonstration Farm near Ames, IA. Each 20 ft subplot consisted of 10 plants spaced 2 ft apart, with a gap between subplots in a row of 8 ft. Rows were spaced 8 ft apart. Bravo Ultrex was applied to the plot every 14 days and no insecticides were used.
Types of cucurbits with more than 50% of the plants dead by 10 weeks were not considered good trap crops. These varieties were acorn, buttercup, hubbard, spaghetti squash, Turks turban, zucchini, patty pan, and cucumber. Types of squash that had better survival were butternut (23% dead), delicata (24% dead), pumpkin (34% dead), watermelon (24% dead), and ornamental gourds (13% dead).
It is also important for the trap crops to be attractive to cucumber beetles. The average number of beetles per plant ranged from 9.6 to 31.5. Four varieties of squash had the highest numbers of both spotted and stripped cucumber beetles; buttercup var. burgess, buttercup var. autumn cup, buttercup var. sunshine, pumpkin var. gold medal.
Our preliminary conclusions from this trial is that butternut squash and pumpkins may be the best trap crops because they attract the cucumber beetles, and have a high survival rate.
OBJECTIVE 2: Alternative strategies against the fungal disease complex of anthracnose, gummy stem blight, and Alternaria leaf blight.
This trial was located in central and southeast Iowa and was completed in 2004.
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.
Four weed management strategies were tested in Ames and Muscatine, Iowa in 2003 and 2004. Results will be summarized in newsletter articles and other publications.
OBJECTIVE 4: Combine the most promising component strategies from Objectives 1-3 into systems-level strategies that integrate weed, insect, and disease management.
Most of the trials in 2004 were repeated from 2003.
OBJECTIVE 5: Document economic costs and benefits of these new management tactics in comparison to conventional practices.
Economic analyses of the different treatment options are currently being calculated.
OBJECTIVE 6: Transfer the project’s findings to muskmelon growers through on-farm demonstration trials, a web site, quarterly newsletter articles, presentations at regional grower meetings, annual field days, press releases, and an extension bulletin.
We have prepared an introductory web site (http://www.public.iastate.edu/~cucurbitipm/). It includes background information on the biology of cucumber beetles, anthracnose, gummy stem blight, Alternaria leaf blight, and common weeds in Iowa, Minnesota, and Colorado, as well as some basic management strategies. We are currently adding the results of our 2003 and 2004 experiments.
We have also completed a web-based extension bulletin, “Melcast: A Weather-based Disease Warning System for Muskmelon Anthracnose”, that describes the system and publicizes a newly-developed Excel computer program that growers can download from our website to help them use the Melcast system. This computer program will be modified at the end of these experiments to incorporate an improved leaf wetness model developed from ongoing modeling efforts.
We have prepared the following articles:
Gleason, M. L., Mueller, D. S., Havlovic, B., Lawson, V. 2005. A row cover and low-risk insecticide strategy for cucumber beetle management. Annual Fruit/Vegetable Progress Report 2004. Iowa State University Extension: FG 601: 37-38.
Mueller, D.S., Gleason, M.L., Sisson, A.J., Massman, J.M. In preparation. Effects of row covers on suppression of bacterial wilt of muskmelon in Iowa. Plant Health Progress.
Furthermore, we presented our research to growers at the Iowa Fruit and Vegetable Grower’s field day in July 2005, as well as at Practical Farmers of Iowa Field Days.
Impacts and Contributions/Outcomes
Our advisory panel includes the following growers: Ray Jensen (Greenfield), Laura Krouse (Mt. Vernon), Greg Hoffman (Waterloo), Michael Nash and Solveig Hanson (Postville), Richard and Sharon Dix (Janesville), Gary Guthrie (Nevada), Dean Henry (Nevada), John Kiwala (Muscatine), Bob Furleigh (Clear Lake), and a group of Amish farmers from Davis County.
We also cooperated with several growers in Iowa on strategies for cucurbit pest management:
Phil and Nancy Funk (Dallas Center, IA) and Richard, Bill, and Sharon Dix (Janesville, IA) managed one row of muskmelons at each of their farms according to the Melcast system. They are interested in learning to manage the sprays on their own using the Melcast computer program.
Gary Guthrie (Nevada, IA) and Ray Jensen (Henry Wallace Country Life Center, Greenfield, IA) evaluated row covers for control of bacterial wilt.
Greg Hoffman (Waterloo, IA) treated one row of his muskmelon plants with a single application of the systemic insecticide Admire at planting. He also planted one row of melons that was treated with Gaucho (same active ingredient as Admire).