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.

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.

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.

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.

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.

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.