The New Agriculture Network's on-line newsletter with seasonal advice for field crop and vegetable growers interested in organic agriculture.

Vol. 2, No. 4 - June 9, 2005

In this issue

	Improving cropping systems with brassica biofumigants
	Soybean aphids are early in Michigan and surrounding states
	Ballad biofungicide registered for soybean rust and can be used for organic soybean production
	When to take action against soybean rust
	South Dakota State U offers soybean rust publication on-line
	Reports from organic growers - updates added Friday, June 10.

Next issue will be posted June 23. Read previous issues through our calendar of issues.

Improving cropping systems with brassica biofumigants Mathieu Ngouajio, Horticulture, and Dale Mutch, Kellogg Biological Station, Michigan State University

Farmers in Michigan and throughout the nation are constantly looking for ways to improve soil quality, reduce inputs, and enhance yield and produce quality.  Today the need to improve agricultural systems is more important than ever before.  The aggressive competition at the marketplace for most commodities has forced growers to specialize in fewer crops, thereby reducing their rotation options.  The use of cover crops, therefore, can serve as a means to increase biodiversity within a short-term crop rotation.  Brassica cover crops are gaining popularity among growers and researchers alike.  Some of the species commonly used include brown mustard, oriental mustard, yellow mustard, black mustard, field mustard, white mustard and oilseed radish (see photos).  Even within a single species, multiple cultivars have been developed and tested in an effort to improve benefits within specific cropping systems.  An example would be oilseed radish with cultivars like Adagio, Arena, Colonel, Remonta, Revena, Rimbo and Ultimo.  But what makes these species unique as cover crops?

Brassica species and many other members of the Brassicacae plant family produce glucosinolate compounds, which are secondary metabolites.  This plant family includes many cash crops (cabbage, broccoli, cauliflower, Brussels sprouts, kale, radish, mustard), weed species (shepherd’s-purse, wild mustard) and cover crops. Glucosinolates are normally stored within plant tissues. However, upon tissue damage, enzymes within the plant trigger their hydrolysis to several compounds including nitriles, thiocyanates and isothiocyanates (ITCs).  Some of the hydrolysis products, like ITCs, are volatile and have been reported to exhibit biocidal properties on insects, nematodes, fungi and weeds.  Since the use of synthetic fumigants, such as methyl bromide, is being restricted and organic production is growing in importance, the ability of brassica species to produce volatile biocidal compounds makes them perfect candidates for intensive cropping systems.  The use of brassicas to suppress soil borne pests and plant pathogens has been referred to as “biofumigation” and the species used as “biofumigants.”  Pest and disease suppression are not the only advantages of the brassicas.  Species such as oilseed radish have shown high potential to increase soil aeration and to scavenge residual nitrogen left after crop harvest, while improving soil quality through high biomass production. 

Several research studies have recently been published and many are currently ongoing throughout the nation and the world to better understand and quantify the contributions of biofumigants to cropping systems.  Studies at Michigan State University have looked at the use of biofumigants in diverse cropping systems.  For vegetable production, our work indicates that brassica cover crops planted in late summer or early fall can produce a significant amount of biomass before being killed by frost in late October or early November under our local conditions.  The cover crops can also be planted in early spring and killed with herbicide or cultivation prior to planting of the cash crop.  In either case, the plant residue can be incorporated into the soil or left on the soil surface.  However, if residues are left on the soil surface, the biofumigation effects may be reduced since the root system has only 20 to 25 percent of the total glucosinolates content of most plants.  Fall establishment of cover crops reduces the amount of residue in the spring, and therefore any potential interference with planting. This would be beneficial in most vegetable cropping systems, where small seed size requires a well-prepared seedbed.  We have experimented with oilseed radish, brown mustard, oriental mustard and yellow mustard planted in the fall in celery and onion cropping systems on muck soils. Many grower cooperators have observed improved soil drainage, especially with oilseed radish, and early spring weed suppression by all of these biofumigants. In celery production, yield was increased in the systems using the biofumigants at both the research station and growers’ farms.  Soil tests showed high nitrogen content in the biofumigant plots compared to the bare ground system.  Levels of other elements, such as potassium and magnesium, were also higher, but varied with the species used.  Furthermore, soil microbial activity was enhanced in the biofumigants systems.  We are currently conducting a nematode community structure analysis to determine the impact of the biofumigants on both beneficial and plant parasitic nematodes.  Finally, we are collaborating with the University of Tennessee to develop glucosinolates profile of the different biofumigants.

Table 1.  Height and biomass production by biofumigants planted in August in Michigan.

For more information on oilseed radish, see MSUE Bulletin E-2907, Oilseed Radish: A New Cover Crop for Michigan. Or Contact Dr. Dale Mutch (mutch@msu.edu) or Dr. Mathieu Ngouajio (ngouajio@msu.edu).
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Christina DiFonzo, Entomology, Michigan State University

Here is a compilation of regional soybean aphid reports as written on June 2.

Michigan (Chris DiFonzo, MSU)
We found SBA on soybean, June 2, at the Crop and Soil Science farm on the MSU campus. This is the earliest find we've had of any year. Buckthorn is across the street from this field in several directions. It was easy to find them. We sampled 143 plants and 3 plants had aphids. Two plants had nymphs, probably from an alate (winged form); the third plant had an apterous mother with new nymphs, indicating she had been there for a few days. Plants were in the V1 stage. The weather has been great for aphid flight over the past few weeks - sunny, moderate temperatures, and low winds.

Indiana (Bob ONeil, Purdue)
On June 1, we found aphids (28 nymphs & 5 adult apterae) in one of our fields in Tippecanoe County. (Home of Purdue U).  A single colony on one of the 2,562 plants we examined (read: we have no life in Indiana).  My guess is that we are seeing local colonization. We still have SBA colonies on buckthorn. This is the earliest we've seen aphids in this county.  The field was V-1.

Iowa (Matt ONeal, Iowa State University)
Iowa has soybean aphids on soybeans.  Today (June 2) at the McNay Research farm in Lucas County we found a soybean aphid nymph on a V0 stage soybean plant, after looking at over 500 plants.  We also saw several winged aphids that were not soybean aphids. Last year, we found our first soybean aphid on June 8th and populations did not increase beyond 0-10 aphids per plant until July.

Minnesota (Dave Ragsdale, University of Minnesota)
Soybean aphid has been found in southeastern Minnesota.  Alatae were common, each with a few nymphs deposited.  The oldest nymph found was a late fourth instar which indicates that aphid colonization occurred in the last 4-5 days.  We have not yet found soybean aphid on buckthorn although we sample several hundred buckthorn each week, although we have found lots of buckthorn aphid. To me it appears that this colonization is from local sources rather than long distance migration with field edges closer to buckthorn more likely to have soybean aphid or aphids that are easier to locate than fields located some distance from buckthorn. This is the earliest we have found soybean aphid in Minnesota colonizing soybean.  I don't know if this portends to a "bad aphid year" or not.  It all depends on how natural enemies respond to this invasion.  Most soybean fields are just emerging.  No soybean field sampled is beyond V-1 growth stage (unifoliates but no trifoliate yet uncurled)

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Ballad biofungicide registered for soybean rust and can be used for organic soybean production

Willie Kirk, Plant Pathology, Michigan State University

AgraQuest announced that Ballad biofungicide has received a Section 3 label for the control of soybean rust in soybeans. At present Ballad is the only OMRI approved fungicide to control rust in organic soybean production. Ballad's active ingredient is Bacillus pumilus, which when used as a protectant fungicide controls a wide range of fungal pathogens. Agraquest has data from South Africa to support their efficacy. This data is shown in the accompanying figure.

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When to take action against soybean rust

Patrick Hart, Plant Pathology, Michigan State University

Editor’s note: Plant pathologist Pat Hart wrote this update today (June 9) for our conventional newsletter produced at MSU. The information is relevant for organic production. Visit our soybean rust web page for links to state and national organic information.

 Soybean rust still has only been found on volunteer soybeans in a single county in Georgia and on kudzu in four counties in Florida. Scouting for soybean rust continues in states south of Michigan, and if found would trigger intense scouting of soybean sentinel plots planted throughout Michigan. 

There has been some suggestion by members of the chemical industry sales community that spraying fungicides for soybean rust should begin in Michigan when the disease is found in soybeans as far south as Louisiana.  This is not true and would be a waste of money and time.  Due to the intense monitoring for soybean rust throughout the United States, Michigan soybean growers will have sufficient warning to apply fungicides in a timely manner and not before the disease has appeared in northern Ohio and Indiana.
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South Dakota State U offers soybean rust publication on-line

Joy Landis, Integrated Pest Management Program, Michigan State University

The Extension Plant Science, Economics and Ag Engineering specialists at South Dakota State University recently collaborated to produce an 8-page publication on Asian soybean rust. While written with conventional production in mind, you will find much of the information crosses over to organic production. Topics include:

* Where did soybean rust come from? Will it get to South Dakota?
* Rust is manageable: we have time to plot its progress and plan our response
* Soybean stages most vulnerable to rust are R1 through R6
* Droplet size is critical if fungicides are sprayed
* Dealing with soybean aphids
* Some economics and insurance issues

You can download the publication from a pdf file at:
http://agbiopubs.sdstate.edu/pub_description.cfm?Item=ABS205

Instructions for downloading software to view/use pdf files:
http://www.adobe.com/products/acrobat/readstep2.html

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Reports from organic growers

Corn, soybeans, sunflower and amaranth planting is complete.  A small patch of millet will go in soon, and buckwheat in July.  Hay has been cut and raked twice; if the rain holds off, it will be baled before nightfall.

I've been rotary hoeing soybeans, corn and sunflowers.   The next two weeks will tell the tale for successful weed control. More rotary hoeing, flaming, row cultivating are on the calendar.

Southwest – Dale Mutch
In southwest Michigan we had a large rainfall this week—up to 4 inches in some areas, 2.5 in others. Most of our planting is complete and we are looking forward to the crops taking off and growing. 

Indiana
Northeast Indiana – Dan Flotow
Of course the big news for us in regards to weather is the lack of rain. Just the opposite of last year, when it seemed like it rained every other day and we got too much water. This year we aren’t getting enough water. Currently we are 5 inches below normal for the year—much of this deficit coming in the last three months. I think we’ve only received two good (half-inch) rains in those three months. This lack of moisture is starting to make it difficult to work up new ground for planting. On top of that, the past four days have turned very hot. Thank goodness I invested in a drip irrigation system—it will pay for itself this year. The crops that we’ve planted are looking very good, especially those that are mulched.

In the past two weeks we’ve planted more sweet corn, green beans, tomatoes, peppers, Swiss chard, watermelon, cantaloupe, summer squash, winter squash plus some new crops for us—sweet potatoes, dry beans and edible soybeans. This is the second week for our CSA program (Community Supported Agriculture, vegetable subscription program). The bags have been a little short with some crops maturing slower than expected (peas and broccoli).

During the next two weeks we will finish up the majority of our crop planting (more cucumbers, summer and winter squash, melons, sweet corn, celery and okra) and shift our focus to fertilizing and mulching. In fact, today we did some more mulching on the potatoes.

Eastern Central Indiana - Gary Reding
The popcorn is up and going good. It was rotary hoed one week ago, and will be again this afternoon. No weed problems at this point; a perfect stand.

We had 3 inches of intermittent rain in May. No rain yet in June. It is hot and dry, but we still have pretty good moisture. Most first cut hay is cut and re-growth looks good. We are getting ready to plowdown some hay and put soybeans out. They will be contracted for feed.

Central Indiana - George Mears
Corn has been cultivated. There is an uneven stand in clay soils. Horseweed (giant ragweed) that was not killed by cultivation is shading the corn. Foxtails are under control for the most part. Soybeans have been rotary hoed and will be cultivated soon. Beans have about two leaves and are nodulating. Wheat is heading and should start to fill out. The first cutting of hay came off well, but regrowth is not good due to dry weather. The weather is heating up and they are waiting for rain.

Central Indiana – David Swaim
In central Indiana we are very dry, but conditions are not as severe here as to the west in Illinois or to the east along the Ohio border, from what we have seen and have heard from friends.  We had 90 degree temperatures this week, but are still experiencing the effects of three cold weeks in late April and early May.  Growth has been very slow and rooting is very shallow on the light gray forest soils.  We received 0.4 inches of rain the end of last week; it was just enough to discolor the hay that was down, but affected little else.  Last Sunday (June 5) there were 90 mph winds just east of us, but the crops were too small and flaccid to be severely affected directly by the wind, and those dark prairie soils are not very subject to blowing.

We are kind of in a lull, catching up on mowing, cleaning everything up from planting season and walking the fields evaluating stands and early growth.

In this area, there is quite a bit of damage from slow metabolism of herbicides, including severe buggy whipping from pre-emergence application of 2,4-D ester with the atrazine. Also the cold, dry soil conditions have amplified any problems with adjustment of individual planter units: seeds too shallow or too deep, starter too close or too far from the row.

The case of the yellow-striped maize: In one large field of long-term no-till several miles south of here, we are seeing a problem in commercial corn that may require conventional tillage to prevent in the future.  For the first time, areas of that field, which inherently has borderline magnesium levels, are showing the dramatic chlorotic striping of severe magnesium deficiency.  The farm is located on a terminal moraine and is underlain with varying amounts of sand and gravel.  The surface soil is a silt loam.  The low magnesium stunting is worse on those areas we call the "white silt flats."  These tight, reflective soils stay cold longer and suffer poor aeration and moisture infiltration and percolation.  This season, with its prolonged cool period after planting, seedling rooting is unusually shallow.  Split sampling has shown that lime, and to an even greater extent, fertilizer, has stratified in the surface layer. 

We know from researching grass tetany that magnesium uptake is slower under cooler soil conditions and that excess calcium and potassium can interfere with magnesium uptake by grasses.  We have also seen in continuous no-till that magnesium will leach downward toward the B horizon faster than other nutrients even in silts.  Although the siltiest areas show the greatest problem, the pattern is confounded by broad striping patterns caused by uneven distribution of both lime and potash from spin spreader applicators.  The most dramatic of the yellow striped corn appears to be where the amount of applied lime and potash is greatest, i.e. directly behind the spreader tailgate.

Future insistence on newer direct drop spreaders would help, but the solution probably lies in incorporating a ton of dolomitic lime, along with the stratified fertilizer and lime, with conventional tillage this fall and then seeding a fall cover crop if returning to no-till next season. For this season, the operator has chosen to have his dealer apply a foliar spray with manganese-spiked magnesium sulfate, which should green up the crop in a few days. This kind of problem would be much less likely to occur in a rotation under organic management using more manures and tillage.

The beans are finally all planted and replanted and now emerged and the conventional corn is side-dressed.  First cut hay was baled late and it's at least two weeks until second cutting and about three weeks until wheat harvest.  Spraying conventional beans is what we are anticipating. Truck crops have been delayed and need irrigation as well as cultivation.

Questions:  1. What are the best materials you have seen that explain in detail how a cash grain farmer in the eastern Corn Belt can transition to organic production and develop an adequate choice of marketing options?  2.  Which cultivation tools work best or are most cost effective for row crops on silt loams and silty clay loams? For vegetable crops?  3.  Do you use plastic mulch in organic vegetable crop production?  If not, why, and what combination of alternatives do you rely on? 

South Central Indiana – Dale Rhoads
After what was a cooler than normal spring with occasional spikes in temperatures, conditions have stabilized into an early summer pattern of highs in the upper 80s and lows in the upper 60s.

We have had sufficient rain fall. We are a little on the dry side now, but not bad. I am watering some to germinate and encourage growth of salad greens plantings. We are watering heavily in the greenhouse to push tomato growth.              

We will be putting up shade cloth on the salad growing areas this week, this is early this year. We are entering the height of our season, which means doing all tasks every week as needed. Planting succession of salad greens, killing off weeds for planting basil outside, tying up tomatoes, tilling under old salad greens beds, harvesting, some marketing on several new customers, some fruit tree spraying, weeding everything, mulching outside and in the greenhouse, preparing new planting areas for salad greens, trying to get the rest of the sweet corn planted.

Currently we are harvesting each week—cilantro, salad greens, spinach, kale, chard and lettuce. We have started harvesting strawberries for home use (it is a light year) and will begin harvesting sour cherries for home use next week.

We will be doing much of the same as what we have been doing the past two weeks—finish corn planting, tying tomatoes, finishing mulching—will be the major tasks along, with the regular harvesting and weeding planting of salad greens routine.

In out tree fruit production, it appears as if plum curculio (PC) damaged the following percentages of the different listed fruits. Only the Asian pears are a cash crop and everything else is for home use.
Apples—50%
Peaches—no crop this year
Cherry sweet and sour—0% PC damage
Plum—75% damaged
E. pear—50% damaged
Asian pear—10% or less damaged fruit

It appears that PC may have laid eggs in the fruit of one row of Asian pear and nowhere else. It was really hard to tell as all Asian pears got frost damage when the fruits were about half-inch in size. This damage caused surface cracking that was hard to distinguish between the cracks and PC egg laying scars. All the fruits have grown out of the scarring from the frosts. Later we will be able to tell for sure if PC laid eggs there or not. Other Asian pear trees were obviously not hit with PC, even adjacent to E. pears that in their fruiting this year were stung hard.

As listed in the last report, there are additional preventative measures, cultural practices, trapping devices and emergency insecticide applications that can be tried in future years to reduce the number of affected fruit. These numbers of affected fruit, except for the plums, are quite satisfactory—as June drop and thinning leaves on the unaffected fruits, but each year we have a few more affected fruits and it is easy to see where that will end up with[out] additional control beyond the use of the crop protectant Surround.

Illinois
Northern Illinois - Dave Campbell
The weather has been very dry. We've received only two-tenths inch of rain since May 19. It has also turned very warm in the past week. I am waiting for a decent rain before planting my last field of food-grade soybeans, due to some clods in clay areas as a result of spring plowing. There is a decent chance of rain in the forecast for the next seven consecutive days, although we've been hearing the same story for the past week now.

I am currently rotary-hoeing soybeans and plan to start cultivating corn later today. I am also consulting with a couple of researchers to making final plans on setting up my 22-acre field experiment on controlling Canada thistle.

Oats started to head out this past Monday, June 6. Oats and clover look fairly good, although oats will most likely be short this year. No major weed concerns in the oat crop at this time, although there is some lambsquarter pressure that is somewhat of a concern. Lambsquarter pressure has not been an issue in my oats in the past, but it may be this year.

In the next two weeks I'll finish planting soybeans, rotary-hoe beans, cultivate corn, harvest first-cutting hay, plant buckwheat and Sudan grass to experimental field, hand-hoe thistles out of oats/red clover fields, and mow thistle patches around farm.

Questions:
1. I received a call yesterday from a professor from the University of Illinois; he is planning to plant some corn in a test plot today. He was wondering if he should back off a little bit on his intended planting rate of 30,000 population, given the fact that it's getting late. His location is east central Illinois (Urbana area).

2. I may decide to purchase a windrower and a pickup attachment for my Massey 550 combine. Does anyone know of either of these pieces of equipment that may be for sale and are in good condition.

East Central Illinois – Jon Cherniss
Complain, complain, complain! Suddenly it’s 90 degrees and still windy. We were lucky and did get a half inch of rain. The long-term forecast looks like more of the same.

We planted our second planting of tomatoes and peppers this week and will plant winter squash Thursday or Friday (June 9-10). We are doing a lot of hand weeding this week and mechanical cultivation. We also completed our second hilling of potatoes this week. In the next two weeks we will be doing more cultivation and mowing, and as always, our weekly plantings of salad greens. We also plan to seed summer covers of Sudan and cowpeas.

Central Illinois – Dave Bishop
Very dry! Everything is growing very slowly. We are currently cultivating and making hay. We will be processing broilers next week. We are still hoping to plant more vegetable crops if we get some moisture.

Question: Does anybody have a market for certified hulless oats (available in July) or certified alfalfa?

Southern Illinois – Stan Schutte
We finally got a small rain last night 0.4 of an inch, not much, but a lifesaver for a couple more days. Hopefully we can get some more the next couple of days. Pastures are holding up well.

Recently, we have planted the last few groups of produce, cultivated field corn for the first time, rotary hoed regular soybeans, hilled some of the potatoes, and are strawing-down the tomatoes. We also cleaned up all the manure and hauled it to where we will put corn next year. Another task was to prepare the combine for wheat and oat harvest.

We wold our first potatoes at market this week. Beets are about a week off (without the rain). Lettuce would have been done next week, I hope we bought ourselves several more weeks. Sweet corn will begin tasseling next week so it is a good thing we got the rain. We will be moving the turkeys out to pasture soon. If it stays hot, wheat will go in about two weeks. We’ve finished planting the last of the produce. The rest of my markets starts up next week, so hold on to your hats, I'll be on the road about every day.

Iowa
Northwest Iowa – Paul Mugge
Weather conditions have definitely affected our cropping system.  It has been raining about every other day. I haven’t gotten a huge amount of rain, but haven’t gotten any field work done either. I finally got in the field today. Forecast is for a lot of rain for the next week. I had to replant some corn because of the cold, wet conditions inhibiting germination of the untreated seed.

I replanted 25 acres of corn today and rotary hoed soybeans. Some beans will be weedy because I was unable to hoe on time.

I will continue rotary hoeing and will begin cultivating very soon, weather permitting. I also need to mow and bale grass waterways before the thistles bloom. I also have some liquid manure to sidedress in the corn.

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