Using cultivar mixtures to improve pest control and grain crop production

Using cultivar mixtures to improve pest control and grain crop production

Summary

Recent ecological research and our preliminary data indicate that intraspecific genetic diversity can be quite valuable for suppressing pest populations and improving primary productivity. Unfortunately, most fields planted with modern crop varieties harbor very little genetic diversity. Our integrated research and education project will demonstrate the pest-management potential of genotypically diverse cultivar mixtures to better resist populations of plant pathogens, insect herbivores, and even weeds to improve crop productivity. Moreover, because cultivar mixtures tend to improve yield over monocultures even in absence of pests, our work will also demonstrate general improvements in crop productivity by increasing genotypic diversity. Using field experiments at two research centers and farms of three cooperating growers, we will demonstrate and quantify production benefits of planting fields containing several different varieties of wheat. At all these sites, we will compare insect, pathogen, and weed populations and yield among cultivar mixtures and the constituent monocultures.

Objectives/Performance Targets

Performance Target:

Thirty conventional and organic farmers will adopt mixtures on at least 300 acres (ten acres per grower) of small grains to decrease insect, disease, and weed problems and improve production. By employing mixtures, growers will increase yield at least 5% compared to typical monoculture yield monocultures, meaning yield increases per acre will range between 2.5 bushels per acre for organic growers that typically yield 50 bu/acre to 4 bu/acre for conventional growers who average 80 bu/acre.  Conventional growers will also reduce pesticides costs by $20 per acre, which represents nearly 50% savings on a typical preventative pesticide program that costs approximately $37 per acre, further improving profitability.

Milestones

1. Through winter meetings (in-person and webinars) and summer field days, 1500 farmers will be exposed to the idea of cultivar mixtures and learn of the yield and pest management benefits of mixing cultivars together.  These farmers will receive evaluations to capture the state of their knowledge before and after presentations, and their interest in learning more about farming with cultivar mixtures.  Growers with interest will be asked for their contact information (November 2012-March 2013 & November 2013-March 2014).

Accomplishments/Milestones

Milestone 1, associated accomplishments: This milestone is in progress, but for the 2012-2013 season we exposed at least 1094 growers  at 19 separate presentations to our work with cultivar mixtures.  Evaluations revealed that few growers had been exposed previously to cultivar mixtures, unfortunately, very few were willing to share their contact information with us.  Many liked the idea, but were not willing to tied their interest to the idea until we had some performance/yield data to share.  Now that we have yield data (see below), we are hoping to have better success during the 2013-2014 extension season.

Milestone 2, associated accomplishments: We have been unable to survey growers due to a lack of contact information; nevertheless at our project specific field days (see below), we have engaged growers in frank discussions about benefits and limitations of growing cultivar mixtures.  From these interactions, we have a good feel for the concerns of growers.  We will address these factors during the extension season of 2013-2014 to better convince growers that our approach holds potential and to find interested growers to survey.

Milestone 3, associated accomplishments: We held field walks at two of our cooperating farms, attracting 63 agricultural professionals to learn about cultivar mixtures first hand.  We also had field days at our research farms, attracting an additional 260 growers that heard about cultivar mixtures.  In these presentations, we solicited concerns and addressed them with in-depth discussions.

Milestone 4, associated accomplishments: This milestone will begin in the coming year.

Impacts and Contributions/Outcomes

Our research plots for 2013-2014 have been planted at farms of three farmer collaborators (Mertztown and Holtwood, PA, and Clear Spring, MD) and two Penn State research farms (Centre and Lancaster Counties, PA).  

From our 2012-2013 research plots, we continue to compile the results.  Many of the results have yet to be gather yet because we are still sorting the insect samples we collected from each site.  Nevertheless, our yield results strongly indicate production benefits from cultivar mixtures.  Across our 1/8 acre plots at the three commercial farms, yield was significantly higher (6% higher) in the five-line cultivar mixtures than the monocultures (Fig. 1).  Yield from our small plots (30 x 30 ft) trended toward higher yields, but the difference was not borne out statistically (Fig. 1).  

• Yield of monocultures and five-line mixtures on research farms and farmers fields. Mixtures yielded significantly more than monocultures in farmers fields (P < 0.03; 6% greater yield in mixtures), and trended that direction in plots on the two research farms.
• Predation capacity of research plots. Predation of sentinel aphids was significantly higher in mixture than monoculture plots (P < 0.05) in our experiment in Centre County, PA, on Penn State's research farm. This finding is consistent with our preliminary data and our hypothesis that mixtures foster better natural enemy communities than monocultures.

Collaborators: