Evaluating weed control strategies in organic vegetable production

Final Report for FNC08-724

Project Type: Farmer/Rancher
Funds awarded in 2008: $6,000.00
Projected End Date: 12/31/2009
Region: North Central
State: Indiana
Project Coordinator:
Dale Rhoads
Rhoads Farm
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Project Information


Rhoads Farm is in south central Indiana, in Brown County a very rural county of rugged 300’ tall wooded hills, mostly National and State Forests and the largest State Park in Indiana. Our largest town, Nashville has a population of 2000 with 15,000 in the entire county.

Several times in the past we have tried to start a farmers market and in 2008 had eight successful markets. I am an adviser to the local volunteer organic food and alternative health initiative.

In the past I sold mostly to area restaurants, establishing long term commitments/relationships with a number of progressive owner/chefs where we are both invested in the serving of the highest quality of organic produce to the customers.

For 2009 I plan on selling most of my produce at the local market, a road side stand and a small CSA. I am currently changing my operation to give more time to developing value added food and fruit products.

In the past I made most of my money off salad greens, other leafy greens, specialty tomatoes and basil. I am changing that to a wider variety of vegetables more suitable for farmers market. Also my fruit trees are into mature production now and I plan on emphasizing those products in my production plan.

I started 15 years ago with broom sedge covered, droughty, no top soil, and old pasture hillside. You could not have found a worm to save your life. Today the top soil is a rich black 3 inches deep, thick with worms and other soil insects and creatures. The hawks, owls and snakes also are abundant with many additional songbirds and other small mammals that are right at home. Where there was nothing but soil erosion is a healthy bioscape today.

I have been striving for more sustainable organic farming practices since the beginning of my farm 15 years ago. Water conservation practices, manipulation of cover crops to increase soil fertility and less inputs, strip plantings to protect from soil erosion, serving local restaurants in the community and wildlife plantings are among the sustainable practices I have put into action.

For the past two years I have been involved in a project with farmers and university personal in the states of Michigan, Illinois, and Indiana in educating extension agents into how to support organic farming. We identified weed control as one of the critical areas that need further research for organic farming. These trials highlighting new weed control methods that could have an impact on all three of these areas of concern by approaching weed control in a more sustainable and less gas dependant manner.

The highlight of the trials is combining the relatively new techniques of an in-place mulch from roller crimping an over-wintered cover crop and using organic herbicides in various ways and combined with a crimped cover.

These trials were carried out in the 2009 farm season.

In our ongoing search for more sustainable farm practices that also speed up weeding time or suppress weed growth we have made extensive use of organic herbicides and some limited flaming (ie- non renewable.). This has greatly decreased weeding labor and hence improved farm profitability. The organic herbicides are made from essential oils etc…, are contact weed killers and OMRI approved. Care has to be taken to learn which herbicides work with which weeds. The organic herbicides we have the most experience with are Matran, Weedzap, Apple Cider Vinegar and Alldown. Matran and Weedzap are the most effective in our experience. Matran arrives in a most concentrated form saving shipping costs. But we regularly make use of apple cider vinegar and other less ‘potent’ organic herbicides depending on the type of weed to be killed, season and weed types. (There are prior SARE reports that give more details about organic herbicide use. Also note that new herbicides are currently being introduced and could be considered.)

In 2006 we began experimenting with crimping an over wintered ‘winter rye’ as an in-place mulch. The over wintered rye is crimped at the time of flowering and this creates an in-place mulch. We found that in our soils some crops grew better than others in this ‘no-till’ vegetable farming approach. Typically there has been in past years almost no weed growth early in the growing season with the in-place mulch.

We think that this crimping and other in-place mulches/cover crops have a very important role in creating more sustainable organic farming practices.

Brief Summary of Findings:
Overall the crimped rye/herbicide areas grew slightly smaller crops (5-9%) with 50-80% reduction in weed control costs over the more conventional, plastic, mulched or ‘hand’/mechanical weeding technique areas.

Using organic herbicides on summer vegetables planted into a crimped over-wintered rye cover crop, especially relatively short lived crops (70-80 days to harvest) makes a very efficient cost effective growing system if:
1. The crops and soils are suitable for ‘no-till production.’
2. Care is taken to learn the different herbicides. (See prior SARE projects done.)
3. That the weeds that are to be killed can be killed by the herbicides… i.e... grass and certain weeds has not been found to be killed very effectively.

Brief Note on Soil Types:
We have a wide variety of soil types on our farm. But the basic is a ‘channery silt loam’ with a high organic content due to our farming practices. Some of our soils have a higher concentration of clay and these tend to perform not as well with crimped cover crops…i.e…. no-till organic vegetable production. These no till techniques seem to not work as well with some vegetable crops that are more shallow rooted or have less vigorous root growth.

Brief notes on Trials Crops Chosen:
We chose to trial sweet peppers, sweet corn and summer squash.

Planting season:
Because the rye is not crimped until early May at our southern Indiana location, crops that are set out earlier in the year are generally already in the ground. For us, using the crimped areas for what we consider the ‘summer crops’ or frost sensitive crops, those planted or transplanted out after all chance of killing frost is over.

Sweet Peppers
The crimped rye tends to suppress weeds excellently early in the growing season. Then around July secondary weeds begin germinating around the pepper plants which do not tend to form a very complete shade canopy. However due to the plants’ upright growth characteristics they are relatively easy to use organic herbicides to kill any emerging weeds. Hand weeding and or hoeing is generally harder in the crimped rye unless each weed is individually pulled out. Combining crimped rye and organic herbicides is very efficient, sustainable, fast and very cost effective – if the weeds that germinate and come up through the crimped rye are not grasses which the organic herbicides do not kill very well. The grasses make for slow weeding through the stalks of the rye compared to bare dirt hoeing.

Summer Squash
Typically the crimped rye supplies all the weed suppression needed early in the season. For us summer squash is a relatively short lived plant due to pest pressures. It also quickly throws a complete shade canopy over the entire growing area. Unfortunately it is one of the crops that have not done as well in the past in this no-till vegetable production system due to relatively shallow roots. We also think that squash requires a fairly loose soil. In years past we have had suppressed plant size with smaller yield in growing summer squash in crimped rye areas. For these trials we worked the soil a bit deeper and in a 9 inch -10 inch circle around each plant, then pulled the rye back over and had both excellent weed suppression and good plant size and harvests in the crimped rye areas.

Sweet Corn
Sweet Corn is a crop that once up produces a fair shade canopy and is relatively short lived in that most varieties do not go into the fall season when another flush of weeds occurs. There is some control of weeds needed in the row of the corn planting or around each plant, but the organic herbicides will not kill a corn plant after it is 12 inches in height and the spray is kept off the fresh leaf tips… on the stalks. The corn had slightly smaller plant size and slightly smaller ear or harvest size on the crimped areas, but this was more than compensated by the almost total lack of need for weed control. Typically the later weeds that germinate are watched to see if their seed production will be later than the corn harvest and allowed to grow. These are then mowed down after the corn is harvested making for a very fast and efficient weed control method growing corn on crimped rye.

Weed control Costs
Originally we had thought to measure both input of materials and over all weed control costs but have chosen to combine these two into one figure.

Crimped rye is the cheapest and fastest of the methods tried, less tillage, less gas used, no inputs other than the cheap investment of seed and planting the fall prior to the growing season which we would typically have the rye as a cover crop in the winter anyway.

Using plastic is the next cheapest, but does have additional expenses of the need for drip irrigation, removal and disposal of non-biodegradable plastics and drip tapes. It also does not bring any additional organic matter to the soil as the rye does.

Using the organic herbicides has proven for us over many years to be far cheaper and much faster than hand weeding once we learned to use them properly. Typically using the organic herbicides to set up a sterile seed bed to plant or transplant into saves 20-80% of the overall crop weeding costs.

Typical farming methods of tilling, planting weeding were the least cost effective making for a lot of labor in weeding early in the season when typically there is an over burden of farm work to get everything planted, and harvest of Spring and greenhouse crops is demanding time. In some of the trials the costs of hand weeding were as much as 20 times the other methods used.
Mulching is the most expensive of the methods used- but does have significant advantages in terms of soil building and near 0 percent weeding once the mulch is installed. (We have tried a number of different mulches. Half rotted oak sawdust is cheap in our area. The cost is labor applying it. Straw is relatively expensive, but does not provide as good weed suppression and germinates a lot of orphan wheat seedlings, which the herbicides will not kill very effectively.)

Effectiveness of weed control:
The plastic and some of the crimped areas were the most effective methods, once the area is tilled, the plastic is installed, drip lines laid, water managed, wind flap damaging the crop early in the year is controlled, if taken up or partially degraded and tilled in.

The rye areas are easy to manage and provide as good a weed control for about 60-90 days after crimping (May in Indiana.). Then weed production timing (to destroy weeds before they seed – hopefully after the crop is harvested), and organic herbicide or hand weeding measures are needed to be managed.

The mulched areas provided the most effective weed control, but the least cost effective.
Hand weeding is what it is. Once the canopy and the shade from that is up weed pressure goes down dramatically.

Yield and Mature Plant Size:
I have already reported on some yield problems in past years with the crimped rye and suggestions about how to overcome this. Typically in this year’s trials harvests were the same for peppers no matter what treatment, except the plastic produced slightly earlier and slightly longer harvests due to soil warming. Summer squash came on three days sooner under the plastic which can be somewhat important for farmer’s market, but only one week. Yield size was similar in both crops no matter the treatment used. With sweet corn there was a slightly smaller ear size in the crimped areas and slightly earlier harvest (2-3 days) in the plastic growing areas.

Project End Fertility:
The difference is very visible. The crimped areas had increased organic matter, increased biological and worm activity and actually a looser soil at the end of the growing season than the tilled areas, especially in the row compaction from foot travel for harvesting and weeding. Over a period of ten years we would reasonably expect to begin seeing decreased fertility inputs, improved soil characteristics and improved total system benefits of less pest pressures, healthier plants, increased harvests etc…

However the mulched areas experience a very high input of organic matter far beyond even the crimped cover crop. We tend to use bare dirt/mechanical weeding-crimped rye areas-heavily mulched areas in a rotation growing crops that work well with these different techniques with the overall plan of increasing over all farm fertility.

Note- Using these techniques over the 15 years of our farm has produced amazing improvements in soil fertility, biological activity, wildlife on our property. In 2008 while digging some postholes for a shade cloth we discovered that the hard grey clay subsoil is now soft, pliable and a yellowish-reddish color, meaning that the soil ph has changed to depths of over 24 inches enough to release additional minerals and nutrients to even that depth.

This information was presented at the 2009 Midwest Organic Team meeting.

Roy Ballard
Extension Educator
Purdue University
Hancock County, IN

Dale R. Mutch, Ph.D.
Extension Specialist and
Acting Coordinator, KBS Land and Water Program
3700 E. Gull Lake Drive
Hickory Corners, MI
FAX: 269-671-4485
[email protected]

Part of a Report of the Multi-state team not directly associated with this report but part of a Midwestern Team that did its first Educator’s Training in Dec 2009 in MI.

Summary of first conference call
August 15, 2007

• Dan Anderson, University of Illinois Extension
• Roy Ballard, Purdue University Extension
• Dale Mutch, Michigan State University Extension
• Doug Carter, Michigan State University Extension

Dale stated that the overall goal of the grant is to utilize the New Agricultural Network (NAN) to engage Extension educators from the three states in organic farming educational programs led by organic farmers and researchers. In addition, we strive to enhance communications between organic farmers, educators and researchers to better meet the needs of the organic farming community.

MSU has the grant, but Purdue, U of Illinois and organic farmers are critical. The grant period is two years, and includes $15,700 for each state to be used for administration, travel and involvement of organic farmers.

The group agreed to the following general strategy for addressing the grant.
a. Involve the three lead farmers immediately:
- Dave Campbell of Maple Park, Illinois
- Dale Rhoads of Nashville, Indiana
- John Simmons of North Branch, Michigan
b. Agree upon general topic areas and outline for educator training (see below)
c. Develop and conduct survey of educators and organic farmers around general outline – include questions on alternative formats and timing
d. Tabulate and analyze survey results
e. Revise outline per survey results

f. Involve other farmers and other land grant faculty in review of draft outline
g. Schedule and conduct pilot training(s)
h. Assess, evaluate and revise (localize as appropriate)
i. Recruit additional organic farmers and Extension faculty
j. Schedule and conduct appropriate trainings in each state, including on-farm demonstrations and field days

General topics and outline for educator training
• Background on public perception, growth and importance of organic farming and locally grown products – why this is happening and why it is important for Extension educators and land grant universities to be involved
• Develop layman’s working definition of Organic Farming
o Manage farm as an integrated system
o Minimize inputs
o Categories of organic farming – initially focus on
? Vegetables
? Field crops
o Essential elements
o Why are more farmers transitioning to organic
? Personal reasons
? Benefits
• Higher profitability for farmers
• Certification – individual and land/farm
o Requirements
o Benefits of certification
o Process
? Authorized certifying organizations
? Application procedures
? Farm/land review
? Approval
? Length of process
• Review process
• Waiting period for transitioning
? Costs
• Available financial assistance?
? Soils management
o Testing
o Amendments
? Pest management – prohibited and acceptable lists
o Weeds
o Critters
? Cultural activities
o Cover crops
o Rotational planting
o Row planting
o No till
o Etc.
? Marketing of organic and locally grown foods
o CSA’s
o Farm markets
o Direct marketing
o Off the farm
o On the web
? Resources
o Extension
o Agencies
o Web based
o Hard copy publications

The group discussed how to better involve educators and best regionalize our efforts – recommendations
? Use January, 08 conference in Champaign, Illinois for pilot training
o Offer CEU’s as an incentive
o Michigan hopes to use PDP funds to get its educators there
o Develop and distribute a web reference document of science based articles and web sites
? Get more educators to use the NAN website and participate in NAN conference calls – each PI will forward NAN e-mails to their educator colleagues
? Investigate developing a NAN related list serve
? Review and share SAN and SARE bulletins
? Get involved with the Mid West Organic Co-Op

Doug mentioned that the Minnesota Department of Agriculture conducted a series of organic short courses – he will send the final report and assessment to PI’s and lead farmers.

Catherine Twohig from Minnesota has a grant to survey mid-west educators on a similar topic. We will see if she’s interested in doing pre and post tests, and follow-up surveys for this project.

The next conference call is scheduled for Thursday, October 4 at 2:00 pm eastern, 1:00 pm central time.

? ALL – including lead farmers
o Review strategy and outline and comment to Doug by August 30
? PI’s Dale, Dan and Roy
o Investigate and determine how to conduct survey of their colleagues
o Investigate how best to “get the word out” to their colleagues about NAN conference calls and related matters
? Dale
o Investigate developing a NAN related list serve
? Doug
o Involve the three lead farmers
o Draft survey and send out for review by September 4
o Send Minnesota report
o Discuss pre and post testing and assessment with Catherine Twohig

Notes prepared by Doug Carter, Michigan State University Extension


Participation Summary
Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.