zipper spiders – Sustainable Market Farming

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.

Insect Pests in December: Wildlife in our Hoophouse

Mystery Chrysalis

Last week (November 18) I found this chrysalis attached to the center of a Tokyo bekana plant. I don’t yet know what it is. If you know, please leave a comment at the end of the post.

I did learn the difference between a chrysalis and a cocoon. In case you, too, are confused, a chrysalis is the quiescent insect pupa of a butterfly. The pupa is the stage between a larva (caterpillar) and an adult. The chrysalis is a tough-ish, smooth, hardened skin of the butterfly pupa, made from shed skin cells of the caterpillar, and its own exoskeleton. Only butterfly species make a chrysalis. When fully grown, the caterpillar makes some silk to fasten its body to a leaf or a twig. This may be a sling, as in Swallowtail butterflies, or a simple attachment and suspension rod as in Monarchs. Next, hanging down from the attachment point, the caterpillar sheds its skin for the final time, and under the old skin is the thicker-skinned chrysalis. When the pupa transforms into the adult it sheds the chrysalis, to make its way out. Most internet searches seem to focus on Monarch chrysalises/chrysalides, which are definitely very beautiful, but not what I was looking at.

Moths make only cocoons. Some other creatures, such as mud dauber wasps, also make cocoons. Moth caterpillars spin a cocoon from silk and wrap it around themselves while they transform via the pupal stage into adult moths. Cocoons are soft, fibrous and usually tan or beige in color.

**Buck Moth (Hemileuca maia), aka saturn moth**

In October I found a group of buck moths in one corner of our hoophouse. These were new to me and I spent a bit of time identifying them. At first, websites were telling me they were rare, but I soon found out this is not so. Most of our moths flew into webs of the zipper spiders (garden spiders) and ended their days feeding the spiders. Buck moth caterpillars feed on oak leaves and other host plants, but rarely cause much damage to the hosts. Their caterpillars have venomous stinging spines. There is one generation each year. The eggs are laid in the fall, and overwinter and hatch in the spring.

If you get stung by one of these caterpillars, immediately wash the affected area to remove any lingering hairs and venom. An icepack will reduce the swelling, but discomfort may remain painful for a few days.

Imported Cabbage Worm **(Pieris rapae), aka imported cabbage white butterfly**

Lifecycle of the Imported cabbage worm. Clockwise from top left: adult butterfly, egg, caterpillar, chrysalis. Utah State University

Among our luxuriant Tokyo bekana plants I found all too many of these velvety green caterpillars, feasting on our greens and leaving lots of frass. Numbers are low enough that we can probably hand pick them. The imported cabbage worm is the offspring of the cabbage white butterfly, and you may be able to fend them off by making decoy butterflies. They are territorial and will avoid crowding in one spot. Here’s the link to a template: http://goodseedco.net/blog/posts/cabbage-butterfly-decoy

There are several cabbage caterpillar pests and although they can all be dealt with in the same ways, it’s good to know what you are up against.

Four types of caterpillars that feed on brassicas. Clockwise from top left Imported cabbage worm, cabbage looper, diamondback moth, cross-striped cabbageworm.

Another caterpillar pest of brassicas is the cross-striped cabbageworm (Evergestis rimosalis). I was quite surprised to see that the adult moth looks so different from the butterfly of the imported cabbage worm. As a child I was told they looked similar. Not so!

Another is the diamondback moth, (Mamestra brassicae). This one also feeds on tomatoes and sunflowers.

Here’s a link to info on the cabbage looper, (Trichoplusia ni), which is pale green with side stripes of yellowy-green.

Beet Webworm (Spoladea recurvalis)

Adult spinach/beet webworm (Mark Dreiling,
Bugwood.org).

We found quite large numbers of this moth (also known as spinach webworm) on our hoophouse senposai last November. As described by Virginia Tech Extension, the adult moths are typically active in late summer. The caterpillars feed on spinach, beets, Swiss chard and amaranth (including pigweeds and lambsquarters).

There’s a nice source of information on Insectidentification.org

Grasshoppers (Melanoplus spp.) and Crickets (Gryllus spp.)

There are still a few grasshoppers in our hoophouse, but the numbers are not damaging. The ones I’m seeing now are Differential Grasshoppers (Melanoplus differentialis, the ones with chevron marks on their thighs), which eat plants. We also have some Field Crickets. Crickets eat plants, especially seeds and fruits, but also insects.

Biointensive Integrated Pest Management

I have written in another post about biointensive IPM, which is a series of steps to manage pests, starting with the actions that cause least damage to the soil or to other species.

Start by trying to prevent pest outbreaks by growing strong plants, caring for the soil, practicing crop rotation, providing habitat for diverse natural predators,
Next, by using physical controls (also called cultural controls) such as removing weeds that are host plants, using rowcover or netting, handpicking the pests if numbers are small enough.
Monitor pest levels and assess if further action is needed. You can do this while hand picking. Many crops can take 30% defoliation without any yield reduction. In general, monitoring should begin at the seedling stage and continue until after harvest.
When pest levels exceed the Action Level, and prevention and physical control have proved insufficient, biological, microbial, botanical and mineral control measures can be used to reduce pest damage of crops to an economically viable level, while minimizing environmental risks. There are four types of sustainable bio-intensive control measures to choose from, starting with the least toxic solution:
1. Biological control involves either introducing beneficial predators or parasites of the pest species, or working to boost populations of existing resident predators and parasites.
2. Microbial controls refer to the use of fungi, bacteria, and viruses to kill pests. Bacillus thuringiensis (Bt) and the Entrust formulation of spinosad are acceptable if you have USDA Organic certification.
3. Botanical control uses plant-based products for pest control. An example is neem oil.
4. Inorganic (mineral) controls, also known as biorational disease controls, make use of oils and soaps.

Clearing Tomato Plants

These tomato plants have served us well, and their time is up. We have pulled them out of the ground and left them suspended in the twine to wilt, before hauling them to the compost pile. The bed behind the tomatoes is being solarized to kill fungal lettuce diseases. Photo Pam Dawling

Here in Virginia, we pull up our two beds of tomatoes in the hoophouse at the very end of July or early in August. I realize this will horrify people in colder climates. I’ve been there. Every tomato plant was to be cherished until the frost took it. But in hot, humid Virginia, we have harvested from these plants for nine weeks, and the outdoor plants are coming in strongly. We don’t need the hoophouse ones; they’ve grown taller than we can reach, and we’ve lopped the tops off with hedge shears several times. Fungal diseases are to be reckoned with, and we only manage a two-year rotation in each bed, as far as nightshades go. In the past, we grew “high summer” food crops or seed crops, and needed to get the tomatoes out to make way for the new crops. Nowadays we only grow cover crops in the summer, until it’s time to prepare the beds for fall planting.

String-weaving diagram from Extension.org

We use the Florida String Weaving method of supporting our tomatoes. One thing I like about this method is that it is easy to take down, and all you have to store for next year are the stakes, which take less space than cages, or individual T-posts. We have a descriptive list of steps, and also a Worksheet – see below.

Another feature of our life with our hoophouse tomatoes are the Peanut Root-Knot Nematodes. When we pull our tomatoes, we examine the roots and carefully remove the ones with nematode lumps in them, usually to the parking lot on a dry sunny day, to die in the heat and be run over by cars. We don’t even want to send them to the landfill, because we don’t want to do anything that increases the number of nematodes anywhere. Nematodes need a film of water to survive, and the parking lot deprives them of that.

Cucumber roots with nematodes (see circles). We forgot to take photos of the tomato roots.
Photo Pam Dawling

We spread the tomato clearance job out over a week, doing one step each day, so we don’t have to be in the hoophouse after 11 am, when the temperature becomes unbearable. After harvesting all the fruit (ripe and unripe, separately) in the first bed, we pull up the plants and check the roots. If we see nematode lumps, we carefully cut off the roots and take them outside. We mark the area with a blue flag in each corner, and later measure the distance from the end of the bed and mark the problem area on a map of the beds. This is in case the flags mysteriously fall out.

When we plan the winter crops, we plant the more nematode-resistant crops in the infested areas.With the non-nematode infected plants (most of them) we shake the soil off the roots to speed up the wilting. Plus of course, we don’t want to be removing precious topsoil from the hoophouse! We leave all the plants still hanging in place in the rows of twine, to dry out for a couple of days. We are going to haul them to the compost pile, and it’s a lot less work (fewer cartloads) once the plants have wilted.

Cutting down through the layers of twine in preparation for clearing string-woven tomatoes. Photo Pam Dawling

The second day, we collect up the plant labels and put them in either the “Successes” bucket or the “Failures” bucket according to whether we want to grow that variety again. We cut the twine, pull out the long pieces and collect them in a trash bucket. We don’t try to save the twine, partly because it would take a lot of time, and partly because we don’t want to use twine that might be infected with fungal diseases. The easy way to remove the twine is simply to cut downwards beside a stake, through each of the pieces of twine, then go to the next stake and do the same, but this time gather the twine in the non-knife hand. Next, slice down the other side of the same stake, to reduce struggle, and make the lengths of twine easy to pull out! We use sisal twine, so we let the small pieces, which were wrapped around the stakes, drop to the ground. Most of them will get collected up when we pull the stakes, and a few will go with the plants to the compost pile.

Gathering the lengths of twine after cutting at both sides of each tomato stake. Photo Pam Dawling

Tomato clearance, after cutting and pulling the twine, and removing the stake extenders in the near bed. The bed to the right still has the extenders in place. Photo Pam Dawling

The third day we pull up the stakes. To reach the full height we needed, we have tied an extension stake onto each one, so first we remove those, then we pull the stakes that are in the ground. We like to use a T-post puller for this job, as it gets the wood posts out nicely without breaking them off in the ground. We only use the wood stakes for hoophouse tomatoes once, and the next year we use them outdoors, often for the snap peas. This is to reduce spread of diseases. When we pull out the metal T-posts we scrape the soil off, then spray them down and scrub with a brush.

Our (welding-repaired) T-post puller makes fast effective work of removing wood stakes too. 15 seconds per stake.
Photo Pam Dawling

When I’m collecting things togethe, I throw them into clusters as I work, and make them ready to move easily. Photo Pam Dawling

The fourth day we haul the wilted plants to the compost pile. We make a little effort to keep the zipper spiders in the hoophouse, but they have minds of their own! We do gather up any egg cases we see, and hang those on the metal framework of the hoophouse, to provide spiders next year.

A large zipper spider in our hoophouse in early August. Photo Pam Dawling

Zipper spider egg cases overwintering in our hoophouse.
Photo Wren Vile

On day 5 we rake and (if in time) sow a summer cover crop. We like to use soy as a warm weather legume that will supply some nitrogen, but it needs 6 weeks to be worthwhile. If we are a bit late, we’ll just sow buckwheat. We need our first bed for fall and winter crops on September 6. The others won’t be needed until Early October or later.

The steps for the second bed happen one day later than they happen in the first one. See the worksheet to get the full story.

Hoophouse Tomato Clearing Worksheet

If you live in a cooler climate than I do and you want to learn about keeping tomato plants growing (and accessible) in a hoophouse, read Andrew Mefferd’s book The Greenhouse and Hoophouse Grower’s Handbook. There he explains the lower and lean method of supporting tomato vines.

And I’ll close out with this photo which shows a tomato stem that I accidentally broke when doing the first round of stringweaving. I bandaged it back together with electrical tape from our drip tape first aid box. In the past I have also repaired stems with band aids. It works really well and the plants recover to live a normal productive life.

Yes, this really works! Tomato stem repaired with electrical tape 5 months earlier.
Photo Pam Dawling

Growing for Market article about sweet potatoes; zipper spiders

The August Growing for Market magazine is out, including my article about growing sweet potatoes. There is (of course!) a whole chapter in my book about sweet potatoes, and I’ve written previously in GfM about harvesting, curing, selecting roots for growing next year’s crop, and storage (September 2007). And also about starting sweet potato slips and planting them in spring (Feb 20007). And the harvest (twice) and starting the slips are covered in my blog too.

This time I wrote about growing the sweet potatoes out in the garden or field: varieties, crop requirements, when to plant, making ridges, using biodegradable plastic mulch, stages of development (roots first, then vines, then potatoes); and pests and diseases.

Also in this GfM is a good article by Joanna and Eric Reuter of Chert Hollow Farm (who I’ve mentioned before., when they decided to drop organic certification). They write about their 12 or so varieties of garlic and how they market them for specific uses such as roasting, eating raw and sauteeing.

The editor, Lynn Byczynski, writes about her son’s wedding and the flower arrangements she made for the big day. Chris Blanchard writes about Gardens of Eagan farm in Minnesota. Once owned and operated by Martin and Atina Diffley, it is now owned by the Minneapolis Wedge Food Co-op. It has expanded and now hosts a few satellite farms which help supply all the broccoli the Wedge needs. Eric Plaksin of Waterpenny Farm (not too far from Twin Oaks), writes about when he broke his foot, and makes suggestions to help other farmers be (somewhat) prepared for adversity, so it’s manageable. And lastly, Gretel Adams writes an inspiring article about growing bulbs and corms for cut flowers. A good read all round!

And, on a different topic: Does anyone know if zipper spiders eat hornworms?

Zipper spider on tomato plant. Credit Wren Vile — Zipper spider on tomato plant.
Credit Wren Vile

We get tobacco hornworms on our tomato plants. Outdoors, they usually get parasitized and do little damage. But the mother of the parasites doesn’t fly inside the hoophouse, and in there we sometimes have to handpick the hornworms. These things get big! And are hard to squash! This year we have lots and lots of these zipper spiders, and few hornworms. I never seem to find zipper spiders eating, but they must, because they grow fast. Anyone know what they eat?