Pest Control in Cucurbits Using Paper Mulch and Intercropping

View the project final report

• 2013 annual report

Commodities

• Fruits: melons
• Vegetables: cucurbits
• Additional Plants: ornamentals

Practices

• Crop Production: intercropping
• Education and Training: on-farm/ranch research
• Production Systems: general crop production

Description of Project Purpose:

Production of cucurbits becomes more challenging with the presence of various pest populations, such as cucumber beetles (Acalymma vittatum), squash vine borer (Melitta curcurbitae) and squash bug (Anasa tristis). Not only do these pests damage these crops by girdling seedlings (cucumber beetles), destroying the flow of nutrients through the stem (vine borers) or consume leaves and flowers (cucumber beetles and squash bugs), but they may be vectors to diseases that will hinder or destroy the crop. Yellow Vine Decline is spread by squash bugs and cucumber beetles are known to be a persistent vector of bacterial wilt. Prior data from our farm indicates to us that a loss rate comprising 60% of most winter squash and melon vines is not uncommon.

The most common technique for handling these pest populations is to maintain a consistent application of pesticides. However, this is an issue for growers who maintain organic certification or wish to reduce the application of chemicals. Further, continued application of these chemicals often reduces populations of beneficial insects desired by the grower. Many organic growers utilize row covers to exclude these pests. However, covers must be removed to allow for pollination. Further, row covers can present some management issues with respect to weed control and management in windy, unsheltered areas.

Good sanitation practices and selection of resistant varieties can also play a part in reducing losses to these pests. While both are accepted as good practices by professional growers, there is still a desire to grow vine crops that are more susceptible to these pests without the use of chemicals and with a reduction in crop management, all while using techniques that have a reduced negative impact on the environment.

The purpose of this study is to measure the relative success of paper mulch and/or companion plants in controlling pest population in vine crops that are more susceptible to the previously named insects.

Importance – Intercropping

Intercropping (or companion planting) techniques are a large part of the legacy knowledge. Recent research shows some support for the empirical knowledge. Sunflowers have been shown to reduce thrips problems in peppers (SARE Project Number: FS01-140). Companion crops have shown statistically significant control of cucumber beetles in cucurbits (SARE Project Number: LS01-127) with the addition of nasturtium, oilseed radish and tansy. We have recently conducted our own SARE funded study (Project Number: FNC10-814) to establish some effective crop spacing ideas that provide intercropping benefits. Companion plants can be another cash crop, a trap crop or a host crop. Benefits can take the form of pest control through masking, repellant or attractant properties. Other benefits may be through beneficial chemical sharing or the ability of one crop to be a nurse crop for another. Regardless of direct companion planting benefits, a diverse and complimentary system leads to healthier growing conditions that do not require additional inputs.

The Genuine Faux Farm is dedicated to maintaining companion planting practices but has found it difficult to continue with companion plants due to production challenges brought about by the scale of the operation. The root of the problem appears to be based on weed control issues. Companion crops often have different spacing and planting requirements. As a result, most cultivation is performed using hand tools, which can be effective if the available labor pool can complete the task within the window of opportunity for controlling weed establishment. However, weather conditions provide limited windows for cultivation and the application of organic mulch. Planting times may differ between companions, which add further complications to the cultivation plan. Failure to control weeds in companion planted fields reduces the effectiveness of the companion effect and decreases crop yields.

Discussion with other growers of a similar size reveals that most still do not consider intercropping at this scale to be a viable option. In most cases, this has more to do with a lack of information on successful companions. On the other hand, planning for and executing systems with companions is a difficult task. Growers of this size will not adopt a new practice if the perception is that it will introduce inefficiency to a system that is already difficult to maintain. It is our belief that we could convince others to include companion planting in their growing techniques if we are able to illustrate methods that can be adopted with acceptable changes in current systems. It is possible that successes in this area could reduce reliance on chemical applications for pest control.

Importance – Paper Mulch

An increasing number of horticulturalists are finding ways to use plastic mulch as an important component of their growing systems. However, many indicate that, while it appears to work in reducing weeds, it seems to be incongruous with a sustainable operation that hopes to minimize negative impacts on the environment. Paper mulch has been considered as an option on and off for some time with a study as early as 1996 comparing plastic and paper (Project Number: AS93-007). For example, a prior study in Vermont (Project Number: FNE05-562) illustrated complete failure of paper mulch due to splits in the paper at the point the mulch was laid. Another study in 1988 suggested that paper mulch may not be adequate for larger scale operations (Project Number: LS88-011). However, neither of these studies considers some newer developments in the product, nor do they illustrate the intention of the researchers to determine what needs to be done to make application of the product efficient and effective.

In addition to weed control, there have been anecdotal and research-based results that suggest synthetic mulches may aid in controlling pest populations. Of particular interest is a study mentioned in the prior section (SARE Project Number: LS01-127). The study shows a combination of coated mulch and companion plants to be significantly beneficial in the control of cucumber beetles. The University of Florida also performed a control vs 6 treatment study that included plastic mulch as a one of several controls for pests in that region with some success (ACCESSION NO: 0200846 SUBFILE: CRIS). Our own preliminary research indicates a reduced loss of cucurbit seedlings on paper mulch. However, we find no similar studies involving paper mulch. It is our opinion that the paper mulch option will not be considered by most growers until research is undertaken to illustrate benefits in addition to a reduction in disposal costs to the environment and the farmer.

 Research Plan:

• Research Question: Will the application of paper mulch and/or the presence of companion plants intercropped with cucurbits reduce pest pressure with an appropriate cost/benefit ratio for a sustainable operation?
• Scope: This study will be implemented on cucurbits known to be more sensitive to the following pests: cucumber beetle, squash bug and vine borer. We will select open pollinated squash and melon varieties that have had a history of crop loss due to these pests.
• Control: Each replication will include a bare soil, no companion planting of the selected cucurbit varieties. All plants will be transplanted. Only cultivation for weed control.
• Treatment A:   Plants will be transplanted into heavy-weight paper mulch.
• Treatment B:   Plants will be transplanted into bare soil with a nasturtium companion row. Only cultivation for weed control.
• Treatment C: Plants will be transplanted into heavy-weight paper mulch with a nasturtium companion row.
• All treatments: Cultivation between rows (where mulch is not covering soil) will be required to avoid any bias introduced by volunteer plant proximity. Irrigation drip tape will be provided to all rows. Transplant spacing will be the same for all rows.
• Variables: The independent variables are the inclusion of paper mulch and/or the presence of a companion crop. Dependent variables include pest presence, plant loss, yield and farm resource use.
• Controlling External Variables: Processes such as cultivation, mulch, irrigation, etc will be undertaken on each treatment within each replication in the same time frame. All replications will be completed in a time frame that is as close as possible given resource ability. Cultivar choices will be consistent across treatments. Data collection will occur away from the edges of each treatment block.
• To avoid destruction of the paper mulch by deer, we will be placing a single strand fence around the plots used for the study to discourage their traffic.
• Replications each year: Two replications will be provided in year one. We will explore the option of increasing replications in year 2.
• Randomization: We will employ a pseudo-randomized approach by first indicating where the companions will be within the treatment blocks, followed by the paper mulch.
• Time Replications: A two-year project provides an opportunity to show research validity across seasons.  We will make adjustments to the mechanics of the study, but not the substance of the research design, if it is found to be necessary for year two. Any modifications made that were necessary for study success, but substantively alter variables will reduce the value of the first year’s results for comparison. However, they will be made if the current plan is insufficient for accurate results.

TIMELINE

• Winter 2012/13 – Identify cultivars, order seed, order paper mulch, field plan and finalize research design. Identify basic cost numbers and prepare data collection materials, including field action recording. Acquire drip tape attachment for mulch layer. Make repairs and adjustments to mulch layer.
• April 2013 – Start seedlings for project
• May 2013 – prepare field for transplants
• Late May 2013 – prepare seedbeds, mark out study grid in field, lay paper mulch, transplant seedlings
• Late May 2013 – place insect traps, begin photo record, record plant transplant numbers
• Growing Season 2013 – collect insect trap data, maintain photo record, maintain vine survival numbers, field notes and field action data.
• August-October 2013 – collect yield data (weight and count) and sales data (for cost benefit analysis), continue photo record
• Winter 2013/14 – SARE reporting, evaluate research data and effectiveness of design. Make adjustments as needed.
• 2014 repeat cycle with any necessary modifications for 2^nd time replication.

PREVIOUS RESEARCH

For literature review, please see prior section.

 Prior research indicates to us that there has been interest in each of the following:

• Intercropping for the control of pests in cucurbits
• Plastic mulch for the control of pests in cucurbits
• Paper mulch as an alternative to plastic mulch

The extension of previous research provided here is to establish a beginning body of knowledge with respect to the value of paper mulch in sustainable growing systems for reducing losses to cucurbit pests.

OUTREACH

•  Farm blog and website
• Submit research for presentation opportunities at various conferences, including Small Farmers’ Conference, Practical Farmers’ of Iowa and the Midwest Organics Conference.
• Submit a proposal for a webinar on the topic of intercropping and paper mulch results and use.
• We will remain open to other opportunities for publication or education in this area, including guest speaking events for other interested persons.

EVALUATION

Dependent variables include pest presence, plant loss, yield and farm resource use.

Pest Presence:

We will focus on the presence of the three pests listed in the introduction (cucumber beetles, squash bug and vine borers). Appropriate traps will be set to collect information about the presence of these insects in each treatment block. Traps will be refreshed throughout the season after counts have been acquired. At present, we anticipate a weekly trap count and reset rate. Traps will be given an overview check each day and the trap count and reset rate may be increased if pest pressure is sufficient to fill the traps prior to the scheduled count/reset date. It is possible that photo records will be used to provide depth to the recording process.

Plant Loss:

Plant loss will be recorded by actual counts and by photo records. Plant loss rates will be recorded only up to the point that plants begin to sprawl (vines over 2 feet long) and observation of this data will no longer be feasible. From that point, photo records from the same field positions will be taken on a weekly basis.

Yield:

Yield will be measured at the point of harvest by maintaining records of fruit count and total fruit weight for each treatment/replication section.

Farm Resource Use:

Field notes and a field action log will be maintained. This will include labor efforts to maintain control of weeds and other appropriate tasks, such as irrigation and harvest. Labor costs and any other direct costs will be maintained for analysis of cost/benefit data for each treatment.

Weed Pressure:

Photo records will be used to show weed pressure levels. We intend to suppress this variable by increasing manual weeding presence in these fields during the study. The effort of weed suppression will be reflected in our farm resource use data.