Tuesday, May 25, 2010

Root Maggots

Members of the cabbage family (and onions: see below) are sometimes damaged by the larvae (maggots) of a fly that looks a lot like a small house fly.  The flies lay eggs at the base of the plant.  The eggs hatch and then the maggots feed on the roots. Plants like broccoli and cauliflower will then wilt easily during the day, because they can't transport enough water up to the tissues with their reduced supply of roots.  The plants may simply fail to thrive, and the leaves can have a shriveled appearance.  If you clear the soil from the roots you may find there are not a lot of side roots, and you may see some of the maggots, which are 1/8 to 1/4 inch long, and white.  The plant might be saved by drenching the roots with a rotenone or pyrethrum solution, and pulling soil up over more of the stem, which can root along the stem.  Often though, it's more practical to pull the plants so you destroy the larvae, and replant.

The damage is most noticeable and distressing when the maggots get into radishes (which, after all, are enlarged roots).  You can sometimes see the actual maggots when you pull the radish, or at least see the brown tunnels along the top and sides of the radish.  If the soil clings in clumps to the taproot below the radish that's often a clue there are maggots, since in our sandy soil that wouldn't otherwise happen.  If you're not squeamish, part of the radish can often still be eaten.  But those radishes will be hotter.  The radish at the top of the post has not been damaged by a root maggot - notice that the soil did not cling to the root, as well as the absence of tunnels.

The key to prevention is to keep the fly from laying eggs at the base of the plants.  Pieces of cardboard, tar paper, or old carpet can have a slit cut to the center, a small circle cut for the stem, and then slipped around the stem to lie flat against the ground.  I haven't ever tried that method. What I've usually done is put wood ashes around the stem, or along the row of radishes, which in theory makes an inhospitable place for the fly to lay eggs.  I've had only moderate success with radishes doing this, but haven't had any problem with the maggots draining energy from my larger plants since I've done this.  Haven't yet done it this year even though the plants have been in the ground for a week.  This is a mistake, and I need to get to it soon.  I reapply the wood ashes after every rain that washes them away.  Right now it's hot and dry and so I'm watering a lot, making it impractical to keep reapplying. (I don't have root maggots yet this year.  These are pictures from last year.)

Some folks in the community gardens haven't had any trouble at all with their radishes, and others of us have had.  Considering these are flies you wouldn't think they'd stay in a plot, so I'm not sure what the reason is.  It might be a timing issue.

Onion maggots are a different species.  The fly lays one egg generally at the soil line, and when it hatches and starts to eat, the greens will start to yellow and maybe wilt.  When this happens there's no point in trying to let the onion continue to grow. You will usually find the maggot at the base of the onion itself.  Throw the onions or at least the maggots in the trash, not on the ground. Read more about them here. We also have onion maggots in the community gardens, but they haven't been a significant problem.  Or at least, they haven't been a significant problem for anyone except JP, who typically gets his shallots in very early.  One of the lessons is that the timing of planting can make a huge difference in protecting us from the emergence of some pests, or in trapping the pests in plants we can later discard, leaving our crop to grow on .

The surest and safest way to protect plants from root maggots and many other pests is to cover them with a grow fabric made of spun polyester.  It does warm the plants somewhat (we don't need that) and reduces the light transmission marginally (which is fine for us).  It's a nuisance to deal with, but very effective.  I've never done this for root maggots, but last year I covered my cucumbers for 3 or 4 weeks to give them a head start over the striped cucumber beetle.  More on that later.


The cutworms are out in full force right now.  They are the caterpillars of a fairly nondescript moth, and I explained about protecting your transplants with a cutworm collar here: (scroll down to "adding a cutworm collar").

One of the things I do with seedlings which are impractical to protect with collars, is to leave a few weeds in the row so there's something to eat besides my seedlings.  About the third week of June the cutworms will have pupated, and/or the stems of large plants will have gotten large enough and tough enough so you can remove the collars and weed close to the plants.  As we've had a warm spring it may even be possible this change will take place by mid-June.

I find a few when digging transplant holes or weeding with a hoe, and dispatch them then. They usually curl up when you find them, but they may be out straight as well.  They eventually grow to about an inch, (which this one was) but you may find much smaller ones now, just beginning to feed and grow.

Thursday, May 20, 2010

Saving Milkweed

Milkweed is one of the most beautiful flowers we can grow in the garden, and the fragrance is intoxicating.  It's also food for monarch butterfly larvae (it's the only food the caterpillars eat).  This site even suggests planting it for that purpose.  Lots of other insects and bees love the nectar too (see the small bees at the upper left of the blossom in the picture). Monarchs are so challenged with loss of habitat in their winter grounds in Mexico that it's a privilege to do everything we can to help their numbers remain high. 

In the garden it seems to be a weed, but in fact except for its inconvenient size and shade (which in our hot garden can be an advantage) it really doesn't behave like a weed.  The root is one substantial tap root, which reaches down a considerable distance, and therefore brings up minerals from below the level that other roots typically reach.  Because it doesn't have much in the way of lateral roots it doesn't interfere with the growth of nearby plants. So it's a great way to grow organic matter for next year's garden.

So I leave as many milkweed as I possibly can.  This year I designated a spot for them, approximately where they were last year - but instead they have moved (or been dragged by the tiller?) elsewhere.  Once the plant matures the long roots stay in the garden and send out runners from which new plants will emerge.

Here are a couple of pictures of the plants just emerging- the shoot can also have a reddish cast:

Japanese Beetle Larva

This ugly grub is what the Japanese Beetle looks like at this stage.  Notice how large it is - much larger than the Japanese Beetle itself.  It's these larvae that eat the roots of grass in lawns and destroy large patches.  Reseeding is only moderately successful if there's an infestation of the Beetles, because these voracious grubs will hatch each year.

About 35 years ago my family had a significant Japanese Beetle problem, and we treated both our back and front lawns with Milky Spore disease, which kills most of the larvae.  Enough survive to carry on the disease, and it's only been in the last 3 or 4 years that I've seen any Japanese Beetles in my yard again. So it solved our problem for 30 years.  It's moderately expensive, but only needs to be applied once.  Just google the disease and you'll find tons of sources and information.  I'm pretty sure the local garden centers have it too.

Ideally, neighbors would treat their lawns too, but the nature of the disease is that over time it will infect enough larvae so the numbers in the neighborhood will be reduced.  We treated only our lawn, but it was still very effective. Milky Spore Disease is not a short-term solution for the garden, and is only to be applied to lawns, not gardens, anyway.

Japanese beetles have become more and more of a problem in the community gardens (from which I collected this specimen a couple of days ago), where there are large dead patches of lawn adjacent to the gardens.  They are notorious lovers of zinnias, and so zinnias can be used as a trap crop. In other words, you can grow some sacrificial zinnias to protect other nearby plants that they might like, and you can collect the beetles from the zinnias. Evening primrose (a weed) also serves as a trap crop.  The food crop they attacked most were the snap peas.  In the garden I knock the adults into soapy water (don't try plain water!)  The container of soapy water needs to be positioned under the beetles, since they tend to drop as soon as disturbed, so it's not easy to pick them up.

You may also see miniature versions of this larva, about 1/4 to 1/2 inch in width, and these are the larvae of the masked chafer beetle, related to the Japanese beetle.  The brown chafer eats roots of plants in the garden and is a more significant pest than we're usually aware of, because they're usually at ground level.  When digging in the spring you may find little nests of these larvae. 

These are both related to what I grew up calling June bugs or May beetles (saw one in April this year).  These are shaped like the other chafers, but are much larger, with a dark brown shell.  They are not a significant pest for us in the garden.

What are these Seedlings Part 2

Here's a picture of a marigold (on the left) and a ragweed.  At this stage it's fairly easy to tell them apart, but in a row of marigolds just coming up, not so much.  The marigold has a ring of crushed oyster shells around it just so I don't mistakenly weed it as a ragweed.

Here's a picture of a row of zinnias and marigolds, with various weeds.

Here's a picture of 3 little seedlings from the above picture.  The top plant is a ragweed, and the middle is a marigold..  Notice that the marigold has longer cotyledons (the first leaves), and the ragweed has rounder cotyledons.  The ragweed is darker green and may have a reddish cast to the cotyledons - but that can be true of marigolds too.  The bottom weed I don't have a name for - will work on that this year.  I think it came in on compost and probably isn't all over the whole garden.  It grows about 12 inches tall, and has tiny white flowers.  There are quite a few of this weed in the picture showing the row.  It's color is distinctly yellow-green.

I'm pretty sure this is a zinnia - but at any rate I'll leave it until I'm sure.

This plant (from the row above) is one of my favorite weeds - lamb's quarters, which I grew up calling pigweed, though in other parts of the country another weed goes by the name of pigweed.  This is where latin names are so useful!  This lamb's quarters is Chenopodium album, and is a relative of spinach and beets and is very nutritious.  It's also in the same genus as Chenopodium gigantium, which Johnny's seeds sells as a food plant. I have a few meals of lamb's quarters every spring, and it's usually my first harvest. On this plant you can see the little pearly dusting on the surface of the leaves. Ragweed has now displaced lamb's quarters as the dominant weed in our garden, which is disappointing.

This is a picture of a larger lamb's quarters with a pea plant, and the color is very much the same.  In other words, the lamb's quarters is a blue-green, though it often has a magenta cast to the center whorl of leaves. This is just about the size I like them best, though I'll pick them up to 4 inches tall or so.  After that individual leaves need to be picked, but at this size the whole plant can be thrown in a salad or cooked.

Friday, May 14, 2010

Preparing the Hole for Transplanting

One more essential for transplanting, especially in our sandy, nutrient poor soil.  Because it would take a tremendous amount of organic matter to upgrade our whole garden plot all at once, it's essential to improve the soil around each plant.  I do this by preparing a substantial transplant hole that adds organic matter and trace elements along with fertilizer.  As I mentioned in Plant Positive not Pest Negative, the basic rule of good  gardening is to feed the soil, not the plant.  But at the moment I feed the plant, knowing that over time the whole garden will improve. 

For plants such as tomatoes, peppers, coles, and heavy feeders such as cucumbers, I remove a couple of shovels of soil, put a quarter to a half bucket of compost in the bottom of the hole, add a small handful of pelletized dolomitc lime (high in Magnesium as well as Calcium), a handful of basic 5-10-10 or 5-7-4 fertilizer,* and a handful of kelp or greensand (high in trace minerals).  I mix the fertilizers with the compost, add back some of the soil I removed, and mix it again several times.  I use the extra soil to build up the bowl around the plant.  I dig and fill this kind of hole for cucumbers and squash even if I'm planting them from seed.

The trace elements are essential for really healthy plants, and help build up disease and pest resistance.  Think of them as vitamins.  Vitamins aren't carbohydrates, fats, or proteins, but they're necessary just the same.

Blossom end rot (those first tomatoes that are black on one end) is a physiological problem, not a disease, caused by a combination of uneven watering and calcium deficiency.  Even though tomatoes really like a mildly acid soil, they need calcium enough so that adding a small handful of lime is a good thing for them.

The organic matter that gets added to the soil - whether compost, manure, leaves, or even peat moss:
1) adds trace elements,
2) makes trace elements already in the soil more available for plants to take up,
3) makes the soil hospitable for the micro-organisms that break down the soil into nutrients, *
4) Helps our soil hold moisture and fertilizers we add, which ordinarily leach out of the sandy soil.
So do all you can to add and save all the organic matter you can.  Compost in place the weeds and food plants you pull from the garden, by letting a small pile decompose right in your garden.  Or if you want to keep the garden neat, dig a hole, put the weeds in, and cove with soil.  Bring coffee grounds and the contents of tea bags from the house and mulch your plants with them; both are very beneficial.  Bring grass clippings if you don't put herbicides/pesticides on your lawn.

In the fall, think about bringing leaves.  Ideally, you'd have shredded them first, as otherwise they tend to blow all over the place before they get tilled in.  For those in the community gardens, you can see soil utterly transformed by a decade of adding leaves every fall, at Dan's garden.  I think his plot is B6 and C6, but you won't have any trouble finding it, because the soil is rich and dark and moist.  He's added horse manure this year, but the fundamental soil structure has been built up with leaves.  Last year his potatoes grew waist high.  I didn't even know potatoes could grow that tall.

In an emergency I've just put the plant in the ground, and planned on side-dressing with fertilizer later on.  But this is no substitute for providing organic matter for the roots. 

* There are lots of reasons not to use chemical (non-organic) fertilizers such as 5-10-10:
1) The manufacture of these fertilizers uses a lot of energy, and may be harmful to the people who make them.
2) The fillers in the fertilizer are not regulated or disclosed, and may sometimes contain heavy metals (lead, cadmium, etc.)
3) Chemical fertilizers are available all at once, and so the excess is leached from the soil and may end up in rivers and lakes where the phosphorus feeds algae blooms.  For this reason we're now being encouraged to use 5-2-10 for our lawns, to help keep phosphorus out of Lake Champlain.
4) Because they leach from the soil so readily more fertilizer is necessary than with slower-releasing organic fertilizer
5) Chemical fertilizers are harmful to the micro-organisms we need to encourage in the garden and which make natural elements in the soil available for plants.  Especially harmful to earthworms, too.
6) Because they contain no trace elements our food will be deficient in them too, which is not as healthy for us.  Any heavy metals or other harmful chemicals will, however, be taken up by the plants and we will eat them.

Thursday, May 13, 2010

Transplanting to the garden

This weekend will see the major start of transplanting in our community gardens.  Here are some of the things I think are most important for successful transplanting:

1) HARDEN OFF THE PLANTS  This means increase sunlight and wind over a few days before the plants go in the garden.  Too much sun all at once will sunburn the plants and the leaves will turn white or get white spots.  Often it's a good idea to reduce watering to a minimum too.  The garden is a harsher environment, and you want your plants ready to take in as much water as possible, not panting because they've had plenty and haven't had to grow new little rootlets. It's very important to harden off your plants, even if means delaying your transplanting a few days.

2) COOL, CALM, AND CLOUDY are the ideal conditions for transplanting.  The middle of the day on a breezy, sunny, Saturday is not.  The idea is to shock the plants as little as possible, and help them adjust before they have to face the sun and the wind.  I usually transplant in the evening as well, which gives the plants an overnight to settle in.

3) PLANT DEEPER.  This isn't a universal, but lots of plants are eager to send out new roots along the stem.  Planting deeper also puts the original root ball further from the hot dry surface in our sandy garden, and as the plant grows it will be protected somewhat from fluctuations in moisture.  Plants that root along the stem include all of the tomato family (tomatoes, peppers, eggplants), coles (broccoli, cabbage, cauliflower etc), and the squash family (including cucumbers and melons).  Although lots of people plant their tomatoes quite a bit deeper, I prefer to have a longer distance between the ground and the bottom stems, to help prevent disease. (see 3 entries earlier) That's not necessary if you're mulching.  If the stems are spindly then planting deeper also protects the stem from whipping about in the wind.

4)  REMOVE THE BOTTOM LEAVES!  This is one of the easiest steps to helping your transplants adjust.  Preserve the growing tip and a couple of leaves below it, but otherwise you really don't need the lower leaves on most of your vegetable transplants.  They are likely to yellow and drop off later anyway - or as with lettuce, you'd be removing them to eat.  At the first sign of wilting you can remove the lower leaves even if you don't do it at transplant time.  Your first task with transplants is to help the roots get established.  I routinely remove the bottom leaves from tomatoes, peppers, cabbage, and broccoli.  (I usually start the squash family in place and don't transplant).

5) IN SANDY SOILS TRANSPLANT INTO BOWLS, NOT HILLS.  Our soil in the community gardens is so sandy that anything we can do to help the soil around the plant retain water is a big help.  I plant most of my transplants into a recess, rather than a hill.  This makes watering easier all through the summer. (The advice to plant in hills is to encourage the soil to warm up faster, and to ensure the soil will drain.  Not a problem for us).

6) ADD A CUTWORM COLLAR  Cutworms are 1/2 to 1 inch grey caterpillars that curl around stems  at ground level during the night and eat right through the stem.  In the morning you'll find the plant lying on the ground, and it looks like it was cut off with scissors.  If you dig around the stem in the early morning you'll find the cutworm near the stem. But as the sun rises and warms the soil the cutworm will travel lower and wait to get an adjacent plant the next time it feeds. To prevent this, put a collar around the stem that extends an inch and a half below and above ground.  Wrapping with a few layers of a strip of newspaper is the most practical, and in time it will disintegrate.  JP uses toil paper tubes cut in half.  On plants I really care about I use a strip of aluminum foil, since the cutworms never climb over that, but it needs to be removed about the 3rd week in June, which is a bit of a nuisance. On tiny plants that would get swallowed by a collar, or plants with a short stem such as cabbage, you can try putting 3 toothpicks vertically around the stem, so the cutworm won't feel the soft stem when it wraps around.  not clear if this works.  This year I'm going to try putting some oysters shell pieces (intended to protect fall bulbs from moles) around these stems and see if that works.  I've already lost a few peas to cutworms.  Update:  Paul from the community gardens reminded me this morning that he's used paper or stryrofoam cups with the bottom cut out, as a collar.  And he and I have both learned the hard way to make sure the large end is down, so you don't pull soil up when you pull the collar off later on. 

7). GIVE SOME TRANSPLANT SOLUTION.  Once you've settled the plants in, water them well and add a cup or so of very diluted fertilizer (such as miracle grow or fish emulsion), and/or some sea weed extract. (see a couple of entries earlier).  This helps the root system start to expand, and in the case of the sea weed it boosts the immune system and helps the plant respond to the shock of transplanting.

8) WAIT TO TRANSPLANT YOUR PEPPERS, and probably your eggplants, too.  One year I transplanted about half my peppers into the garden about the same time I transplanted the tomtoes.  The temperature seemed warm enough, and the plants got established nicely.  But the remaining half that stayed in the house under lights really flourished, and by the time I got them transplanted they were much bigger and sturdier than the earlier ones.  Peppers are very sensitive to temperature.  Peppers that spend the night in the low 40's will stop growing for a week, even though they won't show any damage from low temperatures.  So if you've got your peppers, transplant into larger pots if you can (9 oz cold drink paper cups are fine) and wait til the first of June to transplant.  Leave them outside during the day, and bring into the house at night.

Dew Point

For the fourth time this last month, the morning temperature has been about 4 degrees colder in Burlington than the National Weather Service predicted.  You'd think they'd learn, especially when frost is involved.  Last night they said the low would be 34, and now at 5:30 it's 31.  It won't be a surprise if it drops another degree in the next hour before it starts to warm.

One of the keys to deciding if there will be an unpredicted frost is to look at the dew point, which is the temperature at which the air will be so saturated with water that it will condense on colder surfaces.  Warm air holds a lot more water than cold air, so the dew point is not a measure of the actual water content.  The temperature can never go lower than the dewpoint, (but the dewpoint can drop as the temperature goes lower.)  So the dew point is a good guide to how low the temperature can/will go.  If 34 is predicted and the dew point is 32, there's a good chance you won't get frost.  If 34 is predicted but the dew point is 17 (as it was earlier this week), then the temperature is likely to drop, and frost is a good possibility. 

If you're caught by an unexpected frost, the best thing to do is go out as early as you can (before the sun hits the plants) and spray with water.  This will warm the plants and the ground, raising the temperature around the plant. 

The amount of moisture in the air affects plants in other ways.  Really dry air dehydrates plants, and really humid air promotes some fungal diseases. 

When the dew point reaches into the  50's and 60's then we're usually uncomfortable, especially if it's not very warm.  (If it's 90, then the amount of water in the air relative to what it can hold will be lower, and it actually may be more comfortable.)  But by the time the dew point is 70 people generally find it oppressive.  And when it's hot with a high relative humidity our sweat can't evaporate off our bodies, and we lose our ability to cool down.

In the meantime, this next week looks to be great weather.  We could use a little more rain, but in our sandy garden that's almost always true.

Sunday, May 9, 2010

Sea Weed Extract

Sea weed extract is the magic elixer of plant stress protection. There are active hormones in the extract that boost plants' immune systems. It's good to treat plants with this 2-3 times a summer (some have suggested that much more often than this may be detrimental).

At transplant time, flowering, or when plants are under particular stress (prolonged heat spell, or when you notice they are yellowing and you're going to need to side dress) are good times to spray the plants with this hormone mix, which they'll absorb through the leaves.  It is not a fertilizer ( because it's applied at a great dilution), but will help the plants make better use of the available fertility.  By boosting the immune system the plants will ward off diseases and insect pests better - one of the ways to be plant positive, rather than pest negative.

It's mostly my tomatoes that I spray with sea weed extract.  I buy Sea-Com from Johnny's seeds, but there may be other brands available locally.  Look for brands that say they have active cytokinens (though there may be good brands that don't say this).

update:  As we're facing frost tonight I'm remembering that sea weed extract may confer a couple of degrees of frost protection, too, perhaps by strengthening the cell walls.

Saturday, May 8, 2010

Plant Positive, not Pest Negative

In The New Organic Grower, Eliot Coleman gives his philosophy for dealing with pests - both bugs and diseases - as "plant positive, not pest negative."  We should try to prevent diseases and insect pests, which minimizes having to deal with them when they arrive.  As with people, the way to do this is to optimize growing and living conditions, so the plant's immune system is strong and resistant (plants have immune systems!)

The best way to be plant positive is to feed the soil, not the plant.  Every bit of organic material and trace minerals we add to the soil helps build it up so it's able to support plant growth.  Our soil is so sandy that I'm not there yet, and I have to feed plants as well as working to build up the soil.  Even with the compost I add, I tend to concentrate it in the bottom of plant holes, and directly in the rows where I'm going to plant. Over the years  the whole plot gets some compost. For trace minerals I've added greensand (as if we need more sand - but this particular sand is ground rock very high in trace minerals) and dried kelp.  When we add commercial fertilizer we're only adding Nitrogen, Phosphorus, and Potassium.  But there are lots of other elements healthy plants need in various proportions, including Calcium, Magnesium, Boron, and even copper and zinc.  Our soil tends to be acid, and so adding lime adds needed calcium.  But adding dolomitic lime (available pelleted at various garden stores) adds magnesium as well as calcium (magnesium substitutes for some of the calcium atoms in the calcium carbonate.  The pink stone along the interstate cuts in Colchester, or along the lake, is dolomite).  Trying to garden without these added trace elements is like trying to stay healthy by only eating meat and carbohydrates.  Enough calories, but you're not going to thrive without your fruits and veggies.  And you might even need a vitamin pill.

Other things that can help are spraying plants with sea weed extract at strategic times, interplanting herbs and onions to (apparently) confuse the smell of the plants for pests (and spraying with garlic may help deter some insects), planting in small patches so there's not a concentrated stand for insects to attack, and using trap crops.  Sometimes insects prefer a plant other than the crop plant, and you can collect insects on this plant you're willing to sacrifice, and minimize them on your crop.  For example, striped cucumber beetles seem to prefer tomatillos to cucumbers.

The sad truth is that with a community garden it's very difficult to eradicate insect pests, because there will always be gardeners who don't practice good control.  But you can pamper your own plants so that at the least the pests go in search of weaker plants in somebody else's plot - until they, too, learn how to manage them.

Wednesday, May 5, 2010

Planning for tomato diseases when you plant

In Northern Vermont the tomato disease we most often get is septoria leaf spot (as in the picture above), a fungus that lives in the soil and splashes up on plants, and is transmitted through the air, too.  The disease starts with yellowing lower leaves, then brown spots that appear and eventually merge together, and the leaves turn brown and dry up.  By the end of the summer we may have few leaves left on plants.  Without leaves the plant can't produce sugars, and the tomatoes become excessively acid and don't have the complex flavors we enjoy.

Unlike the blight we had last summer, leaf spot doesn't generally directly affect the tomatoes.  They can still be picked and eaten, but they won't have the great flavor a homegrown tomato should have, and the plants won't be as productive as they could be. 

We can do several things at planting time to minimize or delay the onset of this and other fungal diseases.    Although the fungal spores are in the air, the plants are subjected to a heavy load when rain splashes up on the plants from below.  So anything we can do to minimize that will be helpful.

1) Removing the lower leaves keeps them from getting the disease early.  For this reason I tend to plant tall plants without burying the stem extra deep, which is an old-time practice to maximize the root growth.  I'd rather feed and water the existing root ball well. 

2) Just about any mulch will help, if it protects the plant from splash-up from watering or rain.  Straw will add organic matter eventually.  But plastic mulches work too, and red plastic mulch may help productivity.  I've put a clear plastic bag over the plant at planting time (by cutting a slit in the bottom seam), then inserted my cage, and had a bag I could pull up and attach to the cage, preventing even side splash, and helping to warm the plant on cold days.  Weeds will grow under the clear plastic, and I take the bags off around July 1.  If you have lots of compost or composted manure, you can top dress with it, which will protect the plant from soil splash but may also have disease-prevention properties on its own, as some have reported that spraying with compost tea or manure tea will prevent disease. 

3)  Help the plant stay dry.  Water gently with a hose at the bottom of the plant, rather than watering overhead.  Don't grow your plants too closely together.  Alternatively, you can prune so there isn't a lot of excess foliage, especially at the bottom.

4) Do as much as you can to give the plant a strong immune system, by feeding well and spraying with a sea weed extract.  Don't let the plant dry out to the point of serious wilting.  Water deeply to encourage deep roots that will stay hydrated when the surface of the soil dries out.

5) If you have a serious problem with a fungal disease, you can spray with a fungicide which may prevent the disease or treat it.  Update:  The Vermont Department of Agriculture has a new brochure discussing late blight and how to minimize the likelihood you'll get it in your garden.  Some of the listed fungicides (including those for organic programs) are very toxic to the applicator (you).  Use all the product label's suggested precautions when using  any fungicide or pesticide, and in general use only when the air is calm, wear long pants and a long sleeved shirt, and remove your clothes and shower after applying.  Wouldn't hurt to wear a mask or respirator, too.  The brochures are available at Claussens locally, and hopefully at other garden centers.  The same fungicides listed for late blight would also work for the septoria leaf spot we get every year.  I will still plan to use serenade, alternating with a copper fungicide, if necessary, both listed on organic programs.  The leading chemical fungicide may be safer to apply, but some sites have implicated it in the aberrant changes in amphibians that are happening worldwide, so I'll avoid it.

Last year's blight will hopefully not reappear.  It will have died with any organic material that didn't live over the winter.  Potatoes sometimes survive the winter if they haven't been found when digging.  In fact, I maintained a small crop of blue potatoes for a few years just this way.  But it will be very important this year to pull out any potatoes that sprout from last year (and dispose in the trash, not the compost heap), as the blight could have survived the winter in the tubers.  As you can see in the picture below, the blight affected the tomatoes and not just the foliage, and destroyed them in just a few days. Most organic growers in the Northeast lost all their tomatoes, and commercial growers needed to use a very strong fungicide to save their crop.  Some isolated plots were unaffected..  I sprayed my plants just as soon as the blight appeared, and the sun gold cherry tomatoes survived with practically no damage.  This is as good a reason as any to grow them.

Tuesday, May 4, 2010

Planting onions

I grow onions three ways in the garden:

1) From sets, which are small bulbs grown last year and then put into dormancy for the winter, so they're ready to grow again in the spring.  These are only for relatively long keeping onions, since the sets themselves have to keep all winter.  I use sets to grow pungent yellow keepers, and medium storage red onions which usually have sets that are already poking their green shoots up when you buy them.  It's possible to grow your own sets by sowing seeds thickly in summer, collecting the little bulbs in the fall, storing them properly, and planting in the spring.  Too much work unless there's a long-storage variety you crave, and don't want to start them from seed in early spring. Last year a friend gave me lots of onion plants she'd grown from seed, and I didn't get all of them planted.  They spent the winter in the garage, and I'll see if any of them grow this year as sets.

2) From purchased plants, usually of sweet onions, grown over the winter in mild climates (like Washington state), pulled in the spring, and shipped to garden centers.  Also available by catalog, from Johnny's seeds, for example.  The choice of varieties is limited, but this is the best way to grow big, sweet, short-keeping onions. The varieties need to say "long-day" onions. This shouldn't be an issue, but Agway this spring was selling short-day onions - labelled as such - and the chances are they won't bulb at all, as bulbing is triggered by the length of day.  We have longer summer days in the north than in the south, so the varieties have to be specific to the geography.  Depot Home and Garden will get their plants in early this month.

3)  From seeds.  Bunching onions are the only seeds it's practical to plant in the garden and expect to get a crop.  But it's not hard at all to grow seeds under lights.  They need to be started in mid-February to March.  The tops can be clipped as they grow.  I follow Eliot Coleman's advice and plant 3-4 onions together in one place, so I plant 4-5 seeds in each cell when I start onion plants. For bunching onions I plant 10-12 seeds together in a cell, and also plant them this way in the garden.  They are incredibly tiny blades when they emerge, and it's helpful to have a bunch of them together to show up.

I usually grow very good onions considering the nature of our infertile, sandy, soil, and the reason is that I feed them well and water them nearly every day.  I have a friend who had been a market gardener and who now lives where he has to carry all his water by hand up a hill to his garden.  In one of our driest, hottest summers ever ('95) he only carried water  for the onions.  This was an impressive lesson for me.  Onions have shallow roots and need a plentiful supply of water available if they're growing to grow large.  They are also huge feeders.

So this year I'm using some pro-grow organic fertilizer, a little 5-10-10, and some of the compost/silt mixture I just got.  I'll work it into the soil well, make furrows, and plant groups of three onion plants - 10-12 inches apart for the large sweet onions, and 6 inches apart for sets and bunching onions.  When the onions grow they'll push each other aside and grow as big as they would have if planted individually, and it's much easier to weed them this way.  The roots need to be buried, but not much of the plant does.  I usually leave sets just barely sticking out of the soil.  I dig the furrow deep enough so it will collect and hold water.