From: Deborah Cavanaugh-Grant Cvnghgrn Uiuc

Tri-State Organic IP Video Program Session II

Organic Weed Management - March 15, 2007

Audience Questions

with Answers Provided During the Program or by Email Afterwards

Questions for John Masiunas:

Does a brush hoe work well for a stale seed bed in vegetable crops? It appears to smooth seed bed availability.

Answered during program: You don’t want to go too deep with the hoe when using it for a stale seedbed.

What’s the availability of the brush hoes? There is a supplier in Michigan:

Bartschi-FOBRO, LLC, 1715 Airpark Dr., Grand Haven, MI 49417. Tel: 616-847-0300

Question for John Cardina:

How did the corn do that was planted into the hairy vetch?

Answered during program: It does great. Hairy vetch is easy to kill. Once buds form it kills quickly, can be killed by driving on it. There can be a problem with excess nitrogen if N release from vetch is not in sync with crop development. This is most likely to occur if corn emergence is delayed.

Questions for John Simmons:

What do you sell to make $$$ what’s going to market?

With the size of the fields do you have enough to market?

What kind of vehicle are you using, how do you sow your intercrop into corn?

Answers (John Simmons): While field size is modest/moderate, crop totals on the farm are usually 50--80 acres for each crop-- although some 'experimental' or low volume crops might be only 5-10 acres. Acreage of a given crop is determined by a number of factors:

How much do I need to make a sale?

How far out do I want to stick my neck?

How much storage is available to me?

How much volume of crop/time of planting, tending, harvesting do I want to budget to this crop?

How much do I enjoy growing/looking at/tending/shoveling this crop?

What is the potential return on this crop?--

In terms of $$$$$/ac??

In terms of $$$$$$/time spent??

In terms of $$$$$$$/difficulty/time consumed in preparing and marketing the eventual product?

All crops end up in the market in some form. The highest value for most crops I grow is as seed. My highest value seed crop, by the acre, is Open Pollinated Corn. 2nd highest value for most crops is as unprocessed grain for food. 3rd highest value for most crops is as sale for livestock feed. Processing the "grain for food" segment of production into

flour, for example, or further processing into pancake mix-- pushes that segment into highest value per pound. Cost of processing/handling cuts into the net.

Processing feed grains through livestock--hogs/cattle-- increases the value of that product segment. Again, processing/handling costs take a bite. Going to market are the following:

O.P. Corn as seed, whole food grain, flour, baking mixes, feed. Spelt, buckwheat, oats, the same. Rye is mainly as seed. Clover is as seed--although a small amount of clover is harvested as pasture or hay. Sunflowers are marketed as Hybrid Seed. Also as sunflower for crushing--oil/meal, birdseed, livestock feed. We hope to offer sunflower seed as food in the near future. Soybeans are marketed as seed to local markets, food to processors or feed to processors & farmers.

When I intersow into clover I use a tractor mounted "spinner spreader"--the small kind that holds 7-8 bushels of seed. Seed is spread at last cultivation. mid/late July

Questions for Dale Rhoads:

Could you please repeat what organic herbicide you are using in kale on hairy galinsoga?

Answer (Dale Rhoads): Currently there are several organic herbicides or organic products one can use as an herbicide. Some of these are not approved by the state for use as an herbicide, but ….

What we know is available is:

Matran EC- an essential oil herbicide

Weed Zap- an essential oil

Apple Cider Vinegar- We buy it bulk at a 20% solution of vinegar which is the strongest you can buy it. In the grocery vinegar is 5% dilution. We have tried vinegar in different solutions. Below 10% the weed kill drops off dramatically.

LP Flaming- very effective, low cost, easy to use, but is a non-renewable resource.

Alldown- an acidic acid and vinegar herbicide

In January I filed a 51 page report on trials testing the effectiveness of these herbicides with the SARE organization. They should soon have that report available online. [www.sare.org] On the immature hairy Galisoga I generally use a 10-12% vinegar solution and get 100% weed kill.

Does the amount of heat and light affect the effectiveness of your chemical control?

Answer (Dale Rhoads): All the above strategies except the LP flaming are photo-toxic or maybe I should say UV toxic. They all work best with temps above 65 degrees. It is best to apply in the am, after the dew has dried but it does not have to be a bright sunny day as you should know some cloudy days have more UV activity.

This next part is starting to getting into your next question. On days when it lightly raining or weeds are not drying in areas in which I have to kill weeds because the seed crop is about to germinate, I will burn weeds with the LP flamer, so that is my very cloudy day back up plan. The flaming is not burning the weeds to ash, it is only a quick pass over the weeds that boils the water disrupting the cells and the weeds will die.

Have you tried putting a pane of glass over a seeded row to encourage/foster germination of the crop (thereby predicting when the rest of the crop will sprout)?

Answer (Dale Rhoads): Of course that sort of thing could be done, but then you would also have quicker germination under the glass and it would not really tell you when your crop was germinating. We just have enough experience over the years to sort of know given the different seasons, crops and weather conditions as to when something is going to germinate. I try to do a weed kill 24 hours before crop seed germination. My wife always wants me to do it a little earlier. The difference is she does not hand weeding as much as I do and I like to be as energy efficient as possible. Last year I had out of maybe 200 plantings I had 2- 3’ x 100’ salad greens crops that germinated the day I wanted to do weed kill. It was more efficient to kill the crop and start over than to hand weed. Over time with experience you just kind of know when to do it.

What are problems with sawdust mulch? How thick do you apply it to the soil?

Answer (Dale Rhoads): First of all the sawdust mulch we use has several characteristics I did not explain in the video. We use no plastic mulch on our farm. Most organic farms use plastic mulch. We just do not believe in using it. There are some biodegradeable mulches being developed now that are not petroleum based and we are going to play with them some over the next several years, maybe.

The sawdust we use is at least ½ way decomposed. It comes from a sawmill that has been doing pallets for 50 years. Pallets use or saw up much more lighter woods than tannin filled oaks. Over the years this mill has mostly cut poplar trees, white poplars, sycamore etc… So with the make up of the trees in the sawdust and that it has partially rotted avoids many of the tannin or acidic types of problems one might associate with sawdust.

We have no problem with the sawdust mulch itself. As I said in the video I will sort of add in a bit more nitrogen to areas that are going to use it in the next growing season. The problem we do have with sawdust mulch is while it is very effective at about 2” deep, it is more labor expensive to apply it than to use a straw mulch which is more expensive but very easy to apply it if applied before transplanting, but then is harder to transplant into and such playing around and trying different stuff out is what I think will maybe make a farm profitable.

Conventional agriculture tries to control weeds before they get to 4 inches. The slide showed weeds almost as tall as the sweet corn. Was there much of a yield drag to the crop from the weed pressure?

Answer (Dale Rhoads): As I stated in the video that patch of corn was me just playing with those herbicides trying to do as little as possible. I was also trying to demonstrate that these herbicides if used correctly can kill some types of larger weeds.

But no, that corn produced good sized ears of corn that were well filled out and it was very late corn. That was with two herbicide sprayings. I do not recommend growing corn that way. My organic inspector told me of his growing 10 acres of sweet corn in the summer of 2006 using four applications of 20% vinegar spread out over the season.

On the video John M mentioned that all these herbicide are considered restricted products [according to the National Organic Program]. The way OEFFA interprets that is that this cannot be your only weed control method. What my certifier was doing might be pushing the boundaries of that, but he is doing cover crops and rotation which are also weed control methods. He was just sort of trying it out as an experiment.

We do cover crops, rotation and hand weeding, using the organic herbicides to set up a sterile seedbed on some crops and that is all within the organic guidelines. It is also taking us to a place where we will be weed free at some point in the future.

What is Matran – is it an organic herbicide?

See above questions.

What do you do with straw after season? Till under or remove otherwise?

Answer (Dale Rhoads): The Last year was the first time we have used straw mulch extensively. We were before using the rotted sawdust discussed in above questions. Two years ago I did a little experiment comparing sawdust and straw mulch for weed control in kale. Those results showed me to try the straw on a little larger scale in 2006. Basically the straw costs a little more, but is more time efficient, but does not control weeds quite as well. It is sort of a trade off. I think we are going to use straw on all kale in 2007. We just bought a new little transplanting device and have to try it out with straw this week before making final decision. In the consideration is that when we use sawdust we will set up a sterile seedbed and with the straw we till and put down the mulch skipping that step. This is because the sawdust takes longer to apply and some weeds could germinate before application is complete.

As far as what we do with it. We incorporate the straw into the soil when we are planting the over winter cover crop. We applied the straw at about 3 bales per 3’x 100’ row or 1-2” deep. We are growing salad greens in that area this year, which needs a pretty fine soil for planting. I turned the cover crop under two weeks ago and there is some straw stems that may cause some planting problems, but we still have 4-5 weeks before I will need to plant in that area and with several more cultivations which are necessary to kill all the winter rye I think the particles of straw will be broken up enough for planting baby lettuces. Of that 2” of straw applied in spring apx ½ of it was “digested” by the ground by the fall.

What organic herbicides do you use that you said you use 100oz. per gallon?

Answer (Dale Rhoads:) I filed a 51 page report with SARE in January of this year would should soon be available on their website. [www.sare.org] If it is not tell them to get it on there you want to read it. If you need info sooner I can e-mail you part of it. None of the herbicides use 100 oz per gallon. The strongest concentrations of one of the essential oil based products is 10 ozs per gallon.

How do you make a sterile seed bed?

Answer (Liz Maynard): One way is to prepare the soil for seeding several weeks in advance of the regular crop seeding date. Allow weeds to emerge. Kill the emerged weeds just before (or after) seeding or planting the crop. The method used to kill the weeds should minimize disturbance of the soil to prevent bringing new seeds to the surface layers of the soil where they are more likely to germinate. Shallow cultivation, heat treatments (e.g. flaming) and nonselective herbicides are examples of methods used. Seed or transplant the crop with minimum soil disturbance. This method can reduce the number of weeds that emerge after the crop is in the ground. ATTRA has additional information at <attra.ncat.org/attra-pub/flameweedveg.html>

Questions for Anyone:

Where can we find information about the best time to plant cover crops and control them?

Answer (Liz Maynard): See Managing Cover Crops Profitably, available at: www.sare.org/publications/covercrops.htm