Tag: wiregrass

Hoophouse Solarization Ponderings

 

Our hoophouse on solarizing day, August 5. Note we kept the big shadecloth over the roof until we had done the work of installing the plastic over the soil. Photo Ken Bezilla

Solarization Benefits We Hope For

I wrote Solarization of Our Whole Hoophouse on 8/12/26. This summer we decided to solarize the whole hoophouse. We hope to reduce fungal diseases in our winter crops, draw down the weed seed bank, and kill lots of nematodes. We planned to solarize for the whole of August (4 weeks). We started that on August 5, and solarized until September 3, a full 4 weeks later.

A One-Month Break from Usual Hoophouse Work

It was a nice break to do nothing in the hoophouse for a month except run the drip irrigation twice a week. We left the drip tape in place so we could water the soil and keep it alive below the hot zone. It was an unearthly sight to just have a sea of plastic in there, and one of the crew popping in there to turn on the irrigation reported that to was quite surreal to walk barefoot on the hot plastic.

We agreed to use the time to do some infrastructure repairs, and did get a new window made and the other one repaired.

We repaired our big all-encompassing shadecloth and reset the grommets to be a better fit with the spacing of the hooks in the baseboards.

We researched horizontal airflow fans to replace our hippy-rigged box fans, but we balked at the $1000 price tag. Maybe EQIP grants would help?

We did our crop planning for the winter and made a map. We cross-checked the schedule against the map and made sure everything fit. We did some perimeter weeding and laid down landscape fabric.

A Bad Choice Narrowly Avoided

We had the notion that if we had thought of it in time, we might have spread mature compost on the beds before spreading the plastic and killed the weed seeds that landed on the compost pile while we ignored it all summer. We got behind with the mowing, and we know grass and spiny amaranth seeded somewhat on to the pile. Fortunately, we didn’t do that! Sterilized compost has most of its microorganisms killed! Instead, we re-composted the weed-seed-infested pile and got a new pile in the meantime.

Hoophouse soil thermometer showing 100F (38C). Photo Ken Bezilla

De-Solarizing Day

On de-solarizing day we allowed a little lead time (not enough!) to disperse some of the 120F (49C) heat by flinging open the doors and windows. The soil temperature was 100F (38C). The peak air temperature during the month may have reached 140F (60C) although no one wanted to linger in there long enough to really study the thermometer. It had been 80F (27C) before we solarized and is back down to that temperature in as I write this in late September.

Normally we leave the big shadecloth in place over the whole hoophouse until mid-September or so, but this year we wanted maximum heating for the solarization, so we removed it a couple of days after solarizing (when it stopped raining).

We had bought 32’x100’ (9.7×30.5m) plastic which was just right for the footprint of our 30’x 96’ (9 x 29m) gothic hoophouse. We unrolled it down the center bed (it was folded in several concertina folds from each edge to the middle). We mimicked that kind of folding to pack it away.

The first step of removing the hoophouse solarizing plastic: folding the edges to the middle. Photo Ken Bezilla

We started by removing the buckets of rocks we had set round the edges to hold the plastic down. Next we folded both sides to meet in the middle. We got old towels to wipe the underside of the plastic dry. We used some of the drying time to teach broadforking and cultivation and raking to new crew members. We noticed how warm the soil was to our hands.

Wiping the solarizing plastic dry between folds. Photo Ken Bezilla

Next we brought the outer folds in to meet in the middle again, and repeated the mopping operation. Later we thought a sponge mop might have been a useful tool. We used more drying time to start to return things we had stored in a shed during Solarization Month.

Removing hoophouse solarizing plastic: second fold of edges to the middle. Photo Ken Bezilla

We repeated the folding until a simple folding in half made a sensible size for rolling, and ended up with a fat roll of plastic tied up with rope. We wrote on it to deter anyone who might think of using that plastic for any other purpose.

The last fold of the the hoophouse solarizing plastic, making it ready to roll once dried. The dried stems are from a buckwheat cover crop we covered with the plastic. Photo Ken Bezilla.

Disadvantages of Solarizing

I was sad to say goodbye to the hoophouse bell peppers as they were the best we’ve had in years. Usually we keep the peppers until October and do our winter crop planning so that the pepper area is the last planted in winter crops, but we made that sacrifice! For several years our peppers didn’t do well, as the salinity of our soil had got too high. We now do salt wash-downs in September and March. This year the peppers were spectacular! Big plants, huge peppers! Rather disappointing to have to pull them at the beginning of August.

Bullnose pepper in our hoophouse June 27. Photo Alexis Yamashita

Several days into the solarizing I realized with dismay that we had killed off all our zipper spiders and probably their egg cases. The spider corpses were still attached to the framework. Zipper spiders seem to be homebodies. Surely they could have found a way to leave? But mostly they do die at the end of summer, just not on open display. In recent years we have not had any of these spiders outdoors, but many in the hoophouse. They do good work consuming the insects they trap.

Zipper spider on the pepper plants in our hoophouse on September 10 a previous year.
Photo Pam Dawling
Zipper spider egg cases hanging from the hoophouse plastic.
Photo Wren Vile

One big disadvantage of our choice was that the work of bed prep and planting in there after de-solarizing was dreadful! We had hot sunny weather, and the allocation of each day’s prep work took 3 hours or more. By lunchtime it was 120F (49C) in there on many days. Exhausting work! But it didn’t seem worth putting the big shadecloth back in place as we normally remove it around September 20.

Hoophouse fall bed prep. Broadforking in plastic sandals is not recommended! Photo Ken Bezilla

Apart from the workers suffering the effects of the heat, the soil also dried out a lot faster, and we had to keep working (no rest!) to break up the big lumps of soil before they became bricks.

We prepped one bed and got ready to sow. We decided to use wire hoops and a 6’ (2m) roll of shadecloth like we do outdoors for lettuce in hot weather. That worked well, although the bed edges did dry out fast, maybe because the paths were still holding heat from the solarizing. So we had to handwater the bed edges daily for a week or so.

Spinach seedlings from pre-sprouted seed in the hoophouse in September.
Photo Pam Dawling

One of the first crops we sow is spinach, using seed pre-sprouted in the fridge for 6 days. No way would it have germinated in that hot hoophouse soil! On sowing day, the spinach seed showed little sign of sprouting, but we sowed, watered well, shaded it, and it came up great! The extra attention paid off. This spinach will feed us all winter until about March, as we just harvest leaves. By September 21, all the early crops in that bed had emerged (scallions, Bulls Blood beets, tatsoi, radishes as well as the spinach). We needed to remove the shadecloth from the bed once everything had emerged, so the seedlings didn’t get leggy. 12 hours of daylight isn’t so much.

The perennial weeds growing in under the baseboards did not die. Once we removed the plastic the wiregrass (Bermuda grass) raced across the edge bed and started colonizing the next bed. Fortunately juvenile wiregrass is relatively easy to pull up.

De-solarizing our hoophouse. Note the vigorous wiregrass along the south baseboard. Photo Ken Bezilla

Most years we grow summer cover crops in the hoophouse, thus keeping the soil-life active and adding organic matter. This summer offered no gain of organic matter, which I do regret.

Advantages of Solarizing

We have sowed an outdoor seedbed with things to transplant into the hoophouse in October when we have more beds prepared. Work is progressing well, although we’ve had to scramble some days to stay on track.  Because using transplants from outdoors is part of our usual plan, we did not have to make any changes to the beds after the first one, om account of high temperatures.

The advantages of solarizing will become apparent in the next 6 months. Two weeks after uncovering the soil we did find a tiny tomato seedling, but the seed could have been dropped from our clothes after the solarizing month, rather than being a survivor. It was interesting to see it.

For myself, I’m unsure if I’d want to do this again. The advantages are going to have to be huge – like no more nematodes. I’ll write more as the next year unfolds.

Weeds of the Month for November: mugwort, quackgrass and wiregrass

Mugwort and Bermuda grass (wiregrass) Photo Pam Dawling

This month I am going to write about tackling some summer perennials, especially quackgrass (couchgrass), wiregrass (Bermuda grass) and mugwort. November is a good opportunity for digging our invasive wandering perennials.

In October I wrote about winter annual weeds, mostly Henbit, Ground Ivy, Purple Dead Nettle and Chickweed. In September I wrote about late summer weeds, chiefly purslane, velvetleaf, flower of an hour, horsenettle, fall panicum and johnsongrass. In August, I wrote about nutsedges and mugwort; in July, pigweeds (amaranths), warm weather annuals that put out seeds in a “Big Bang” as Chuck Mohler describes in Manage Weeds on Your Farm. In June, I wrote about docks; in May, galinsoga.

Reducing the strength of perennial weed roots and rhizomes

Perennial weeds can often regrow from pieces of roots or rhizomes left in the soil after tillage or digging. Rhizomes look like roots, but they are different. Rhizomes are modified stems, usually growing underground, with roots from each node and buds that can develop into new shoots. Disturbances such as digging and tilling break the dormancy of those buds. In creeping perennials, the roots or rhizomes store carbohydrates that sustain the underground system over the winter and provide fuel for a rapid start up next spring.

When a rhizome grows a shoot, plant hormones from that shoot prevent other nearby nodes or buds from sending up shoots. This is called apical dominance (the node at the apex dominates the other nodes into not sprouting). These chemical messages get weaker over distance, so that, on long rhizomes, after a certain length, the dominance effect is too weak and another node can produce a shoot. That shoot, in turn, also produced hormones preventing nearby buds sprouting. The result is that long rhizomes have a fairly regular distance between shoots.

When rhizomes are cut into little pieces during tillage, the apical dominance applies to each piece, and it can grow one terminal shoot. This is not necessarily as disastrous as it sounds because these are small, weak plants with only a small source of nutrients. They won’t all make it to the soil surface and grow. The danger is in walking away at this point and leaving them to grow.

If we cultivate again before the new shoots have grown enough to send energy back to the roots, or manually pull out the pieces to dry out on the surface, the depleted pieces of root or rhizome may die. Repeated cultivation can chop the rhizomes into small pieces and bury them deeper in the oil. This makes it less likely that the pieces will have the reserves to grow to the surface and thrive.

The strategy is to weaken the root pieces until they give up. Repeated cultivation and drying on the surface can both achieve this goal. This strategy doesn’t work for stationary perennials such as docks and dandelions, which have relatively thick roots, with bigger food stores. Deep burial of taprooted perennials is often an effective first step despite their large food reserves. The storage roots and rhizomes of wandering perennials are not much affected by a change in orientation, but taproots grow vertically in the soil, and if inverted or laid on its side sideways deep in the soil, it first uses energy to develop a new vertical axis. Most tap-rooted perennial weeds grow a rosette of leaves at ground level before growing a flower stalk. Disturbed taproots need substantial food reserves to manage this recovery. See Weeds for June for more about docks.

Bermuda grass has long roots, which can be gathered with some kind of rake or tined cultivator. It is a warm weather grass, and exposure to cold temperatures will at least set it back.

Mugwort has fat, very brittle roots which snap easily. These need to be eased out of the soil and taken away. They don’t dry out easily. We lay ours out on the driveway to dry and get run over by vehicles.

Even simply removing top growth whenever the weeds reach the 3- or 4-leaf stage can be quite effective in further weakening invasive perennial weeds. This may need to be done several times at 3- or 4-week intervals to knock out a bad infestation. For quackgrass, the 3-leaf stage is the time to act. It’s more effective to wait each time until the new top growth has drawn down the plant’s reserves (in the roots) before hoeing or pulling, than to go almost daily after every sprig. Thickly planting buckwheat or other smothering cover crops immediately after tilling helps put extra pressure on the weed, and can reduce tilling passes.

Here is a drawing from Manage Weeds on Your Farm: A Guide to Ecological Strategies, published by SARE

Climate change and C3 and C4 plants

Most plant species (85%) use C3 photosynthesis, meaning the molecules of the first carbon compound produced during photosynthesis have three carbon atoms. During photosynthesis, these plants release water vapor through the stomata, in a process called photorespiration, leaving C3 plants at a disadvantage in high temperature conditions. C3 plants are adapted to cool seasons in either wet or dry environments, not needing full daylight to maximize their photosynthesis. About 25% of the carbon that is fixed by C3 plants may be lost as CO2 in photorespiration. Nearly all trees are C3 plants. C3 grasses have greater frost tolerance than C4 grasses. C3 food crops include spinach, peanuts, southern peas, soybeans, wheat, rice, barley, and cassava.

Common Purslane, a C4 weed.
Photo Virginia Tech Weed ID

C4 plants, which produce molecules of a four-carbon compound, are more adapted to warm or hot weather, moist or dry. They are able to avoid photorespiration, conserving more water. Although many weeds are C3, some of the most competitive ones use C4 photosynthesis. Purple and yellow nutsedge, crabgrass, Bermuda grass, foxtails, pigweeds, and common purslane are C4 plants. C4 food crops include cabbage, corn (maize), millet, sugarcane and sorghum. Weed Science has a 1983 article “Composite List of C4 Weeds” by C. D. Elmore and R. N. Paul. Cornell also has Weeds and Climate Change in their Weed Science department.

The RIPE project is working to improve photosynthesis in C3 crops, for greater food security under climate chaos. Because the growth of C3 plants is limited by available carbon dioxide, they may benefit when levels of carbon dioxide in the atmosphere are higher due to the climate disaster. This benefit may be outweighed by drought stress caused by the increase in temperature. During drought stress, plants close their stomata to conserve water and keep themselves alive, necessitating sacrificing any carbon dioxide intake during that time (meaning photosynthesis shuts down and the plant stops growing).

There is a third photosynthetic pathway, called the Crassulacean acid metabolism (CAM) pathway. CAM plants are succulents, suited to dry, arid conditions..

More Sustainable Weed Management Resources

The Organic Weed Control Rag: Principles of Sustainable Weed Management in Organic Cropping Systems.By Mark Schonbeck

Weed Management on Organic Farms. 2008. By D.M. Finney and N.G. Creamer. Center for Environmental Farming Systems, Goldsboro, NC.

Weed management in organic vegetable production Jed Colquhoun, University of Wisconsin, Madison

Creating a Weed Management Plan for Your Organic Farm, Penn State Extension

 

Growing for Market article, CSA Day, Organic Growers School, VA raw milk threatened

Our hoophouse hydrant with drip irrigation supply equipment.
Photo Pam Dawling

The February Growing for Market issue is out, including my article on drip irrigation, which will help people new to drip get started. I was a reluctant adopter myself, maybe 10 years ago, and I’ve become a big convert. I explain the basics and include the options on tape width, wall thickness, emitter spacing and flow rate, to help everyone get the options that’s best for them.  I have a worked example of the calculation and links to more information. I show how to figure how long to run the system for each week, and the pieces of equipment you’ll need. I talk about maintenance and repair too.

Other articles in this issue include Chris Blanchard on the Food Safety Modernization Act (pronounced Fizma). Of course none of us want to make anyone sick from eating crops we grow, but if you are a farm with average sales of more than $25,000 worth of produce a year , this new rule applies to you. All the details of exceptions and compliance are in the article.

Sam Knapp writes from the Upper Peninsula of Michigan about tackling quackgrass (Elymus repens) without chemicals. We know this as couch grass, a cool weather wandering perennial with long sturdy white roots. It’s not the same as wiregrass, a bigger problem in the South. That’s Cynodon dactylon, also known as Bermuda grass and scutch grass. It’s a fine-leafed wandering perennial that dies back in the winter. If your problem grass is brown in winter, suspect wiregrass; if it’s green, suspect couch grass. Sam Knapp advises on how to deplete the rhizomes of couchgrass/quackgrass with repeated tillage going into the winter and mowing in summer.

Ricky Baruc writes from Orange, Massachusetts, about mulching with cardboard (topped with hay or manure)and silage covers to control weeds and replace the need to till. The editor adds a note that some organic certifiers prohibit cardboard that has ink in colors other than black. Check with your certifier if you are certified organic. Ricky Baruc also uses cover crops, which he crimps and plants into. He is able to manage several acres of intensively planted crops on his own.

If you’ve ever coveted those Bumble Bee tomatoes in the Johnny’s catalog, you’ll enjoy the interview with Fred Hempel, their breeder.

The last article is about winter cut flower planning, and is by Gretel Adams who regularly writes about cut flowers for GfM.

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February 23 is CSA Day. CSAs will be promoting their work and signing up new members. Data gathered by Small Farm Central  showed that the most popular day for CSA signups was  Fri Feb 28. And so CSA Day is celebrated on the last Friday of February to encourage more signups and to publicize the whole idea of community-supported agriculture. CSA is a way for farmers to sell directly their customers. In the original CSA model, people pay for a season’s worth of produce (a membership), at the beginning of the season. The members then receive a box of produce every week throughout the harvesting season. The members are supporting their farmer by paying up front, when the farmers most need the income to get ready for the growing season. Today there are variations on this theme, so look around and see what’s available near you.

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The Organic Farm School Spring Conference is Friday–Sunday, March 9–11, 2018, at UNC Asheville, NC. Click the link to read more and to get to registration. Pre-conference workshops are on Friday March 9, with the main conference 90-minute sessions on Saturday and Sunday. I’m offering two workshops on Saturday, which I’ll repeat on Sunday. This conference tends to offer workshops twice, so people who can only come on one day can choose which is best for them, and fewer people have to miss a topic they are interested in. My workshops are Sustainable Farming Practices and Growing Sweet Potatoes from Start to Finish.

Sweet potatoes on a plate.
Photo Brittany Lewis

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Lastly I want to mention an alert I received from the Homesteaders of America at the end of January. (Note theirs is not a secure webpage)

House Bill 825 (HB 825), introduced by Virginia House of Delegates Barry Knight (R-Virginia Beach), would require herd share dairies to register with the Virginia Department of Agriculture and Consumer Services, be open to premises and paperwork inspections, and adhere to stipulations put forward by VDACS.

“While the sale of raw milk is illegal in Virginia, raw milk advocates have used the concept of herd sharing to obtain the revered, nutrient-dense food for decades. In a herd share agreement, consumers pay a farmer a fee for boarding their animal (or share of the animal), caring for the animal, and milking the animal. The herd share owners then collect the milk from their own animal. No sales occur, the animals are taken care of, and everyone gets to enjoy the magical elixir that is raw milk. Herd share agreements have been in use in Virginia since the mid-1970s” Christine Solem, Virginia Independent Consumers & Farmers Association (VICFA).

On 2/5/18 The Subcommittee #1 recommended striking this bill from the docket. On 2/13/18 the House left this with the ANCR (Agriculture, Chesapeake and Natural Resources) Committee.