Category Archives: Newsletter

It’s hot! But no drought … not quite, not yet.

Not us! Not yet.

“Crunchy” is not an adjective that one usually wants to apply to one’s lawn.  But that’s precisely what the grass is this blazing, thirsty July … crunchy.   And yet, according to the weather service, we’re not in a drought.  Well, that all depends on how you define a drought, now doesn’t it?  What’s a drought?

Hydrologic drought is when the groundwater aquifers, reservoirs, and stream flow are below normal. The massive snows of this past winter recharged the aquifers and while the stream flow for the Christiana River is running between the 24th and 74th percentiles (See ) this is still normal for this time of year on average.  In addition, the large, established trees that rely on subsurface water tables seem in good shape, their leaves full and plentiful. (See  So, accordingly, there’s no drought by these measures, close maybe, but not yet.

A meteorological drought is defined as “a period of abnormally dry weather sufficient to cause a serious hydrological balance.” (Huschke, R.E., ed., 1959, Glossary of meteorology: Boston, American Meteorological Society, 638 p.)  This can be variously defined as an “absolute drought”, a “partial drought”, or a “dry spell”.  An absolute drought is a period of at least 15 consecutive days with less than 0.01 inches of rain or more on any given day. A partial drought is a period of at least 29 consecutive days, the mean daily rainfall of which does not exceed 0.01 inches. A dry spell is a period of at least 15 consecutive days with less than 0.04 inches or more on any given day. If we check the monthly rainfall for June and July, we’ll discover that, meteorologically speaking, we’re not only not in a drought, we’re not even in a dry spell!

But from a farmer’s (or lawn owner’s!)  perspective, it’s quite another thing.  A more recent delineation of the different types of drought includes “agricultural drought”.    Agricultural drought isA climatic excursion involving a shortage of precipitation sufficient to adversely affect crop production or range production.” (Rosenberg, N.J., ed., 1979, Drought in the Great Plains–Research on impacts and strategies: Proceedings of the Workshop on Research in Great Plains Drought Management Strategies, University of Nebraska, Lincoln, March 26-28: Littleton, Colorado, Water Resources Publications, 225 p.) Agricultural drought occurs when there isn’t enough soil moisture to meet the needs of a particular crop at a particular time. Agricultural drought happens after meteorological drought but before hydrological drought. (From: )

Yep. Our crops and your grass have definitely been adversely affected.  Sounds like a drought to me!

For the farmer, the difficulties are threefold:  too much warmth too soon, too little or inconsistent, intermittent rain, and too much sun. Warmer than normal temperatures with abundant rain early in the growing season cause plants to put forth lots of top foliage before they are ready to flower.  If the rain shuts off later in the season as the blossoms are becoming fruits, then the plant struggles to maintain the greenery it initially grew to the detriment of the fruits we look forward to eating.  Warmer than normal temperatures encourage abundant growth, but too much sun, and the tender leaves burn resulting in the loss of entire crops of tender leafy green crops: lettuces, spinaches, etc. and the damaging of newly germinated seedlings.  In fact, sometimes the seeds themselves bake in the too warm soil and never germinate at all.  Rain could to some degree help, but without it, there isn’t much we can do for the seeds already planted. That’s one reason why we do multiple plantings over time of the various crops and have plenty of additional seed on hand.  It’s not a cure-all, but it does mitigate the effects of the drought IF it doesn’t last too long!

So what do we do?  Well, last year we could  water, and did water, sometimes three times a day. The plants were thirsty, and we were glad to do it. Early in the morning, in the evening, and sometimes even in the dark!  With watering cans in hand we walked along the rows, becoming cloudy, indistinct forms after sunset.  There’s something very fairy tale like about watering by moonlight while the deer roam nearby in the hush of the night.

But this year, this crunchy July, we’re giving up our water cans for drip irrigation.  Hooray!  More on that in our next newsletter.


Braconid Wasps versus Tomato Hornworms

          Ah, tomatoes.  We’ve harvested the first of the season.  How plump, how juicy, how tasty!  With such bounty in the offing, we look down the long days of summer with delight.  But there’s a kink in our path, a stumbling block, a veritable bug in the program, you might say.  Tomato hornworms. Neon green and gaudily stripped and dotted, these voracious destroyers can grow to an enormous size and devour an entire tomato plant in a day or two if not stopped.  What to do?  We go on hornworm hunts.  Dawn and dusk are best when they aren’t hiding under the greenery away from the blazing sun, but hornworms, for all their great size, can be elusive, and the hunt time-consuming.  Fortunately, we have allies.

In sustainable agriculture, we use the most natural methods of pest control that we can.  One of these is to encourage natural predators to take up residence in our fields so that they can eradicate those pests that they find tasty and we’d rather be gone.  A good example are ladybugs whose favorite food are the aphids that suck the juices from plant stems. We are now fortunate that braconid wasps have been making their appearance among the tomatoes.

There are three kinds of parasitism in the natural world:  predators, parasites, and parasitoids.  We’re familiar with predators: foxes, hawks, ladybugs. Usually larger than their prey (on the farming, not the Africa veldt scale!), they eat many individuals over the course of their lives.  We’ve also heard about parasites which live in (or on) a single host their entire life, occasionally debilitating, but rarely killing it.  And then there are the parasitoids.  These are the ‘predators’ that seem most alien to us. A parasitoid spends only a portion of its life in or on a host, using the host for food, and in the process, killing it.  Even the definition can give one the shivers!

Braconid Wasp drawing from Pacific Horticulture

Braconid wasps, small black wasps with transparent wings that are rarely over a 1/2 inch long, are parasitoid.  The adult wasp lays her eggs just under the skin of the tomato hornworm, and while the hornworm is munching along on the tomato leaves, the wasp larvae are eating the worm alive from the inside out!  The larvae once ready to become wasps, burrow out from under the hornworms skin and spin cocoons where they pupate until ready to emerge as full-grown wasps.  Usually, only then, does the tomato hornworm expire.  It’s a long, and to human sensibilities, a gruesome demise, but for the braconids and hornworms, it’s the way nature works.

One of the drawbacks of relying on parasitoids to protect crops is that it is a long-term solution.  It may take a year or two for braconid wasp colonies to have grown in sufficient numbers to adequately control the hornworms, and until then our crops are in danger.  So while we will leave a braconid-infested hornworm alone to suffer its fate, we still pick off and feed the others to the chickens.  In sustainable agriculture, we use a mix of approaches; in the end, we and the wasps will win.

For more on braconid wasps, see:

3rd Year Experiment: Trellises

We do a lot of “experimenting” on the farm. What will be more efficient?  What increases the health and productivity of our crops?  What have others tried?  What’s worked or not, and why?  We’re always trying something new (or old, as the case may be with sustainable farming.)

There has been an addition to the landscape at the farm – trellises.  Many plants benefit from trellising: peas, beans, tomatoes, cucumbers, melons, and peppers to name a few.  Any plant with a vine like stalk can be trellised. Trellising is also good for humans; it takes up less room for those with smaller yards and an urge to garden, and it makes picking the fruits a little easier on the knees and back!

Bamboo Trellis

This is our third foray in trellising.  Our first experiment was based on one that we read about in a book by Shepherd Ogden.  He recommended using lengths of bamboo leaned against and tied to each other, to make a sort of elongated tee-pee, with twine tied into a net.  We chose to do this because we had a free supply of bamboo from a friend’s backyard.  We grew beans on these. They were picturesque and worked well until about two-thirds of the way through the season.  The trellises started to collapse because they were rotting through in places.  While wondering why that might happen, we noticed that Mr. Ogden resides in Maine, where the growing season is cooler, dryer, and much shorter – and we live in the middle of a swamp.  As with so many things about farming, moisture is key!

T post and Twine

We used a second variety of trellising for tomatoes last year.  This approach was one that Thera had used on a farm on which she had interned.  In this version, t-posts were spaced every few plants, and twine was tied horizontally between the posts on both sides of the plant to support it by sandwiching it between the strands of twine.  That worked, but required frequent attention: the addition of more twine, the tightening of old twine, and the weaving of errant tomato vines between the strands.

We’re trying this year’s design, which we hope will be an improvement, because it should last for many years, and be much easier to maintain. Each trellis is composed of two 4′ pieces of rebar, two 10′ pieces of ½” EMT electrical conduit, bent into shape, a 5′ piece of ½” EMT electrical conduit, and two set-screw couplings (to join the 5′ piece to the two 10′ pieces), and twine.

As with all new approaches, we sometimes have to learn as we go. To make the trellis frames, we used a conduit bender, a “cut-off saw,” and a metal grinder.  We thought it would be an easy matter to fit the conduit over the rebar, but were frustrated in this when we discovered rebar often has a burr at the point at which it was cut.  About half the pieces of rebar couldn’t be used, and the other half had to have the conduit forced over them.  To respond to this, we borrowed a grinder, to grind the burr off one end of each piece of rebar, and now the conduit fits neatly over just about every piece of rebar.

Two stem, Vertical Twine Trellis

Once the plants are sufficiently mature, a piece of twine will be looped over the plant, wound around the main stem, and tied to the conduit above.  Each plant will be trimmed back to one or two main growing stems which will climb up this single line of twine.  It’s very exciting to see what will result!

For more on how to trellis various types of plants, see:

From E, I , E, I …OH!   the Omnia Humanitas Farm Newsletter

vol 3 issue 2  / June 2011