Archives for posts with tag: humidity

As noted on their license plates, the State of Maine is known as Vacationland. And now I know why.

Rachel and I have driven up to Rockport for the weekend (we’re mixing Rachel’s business and our vacation) and have discovered that the Maine coast is just one big family resort. The woods and forests are pristine, the coastline long and scraggly, and the air is clear and fresh. There are also some good restaurants here (lobster, anyone?).

But, most of all, the climate is perfect. Here we are in the middle of August—the summer’s peak, really—and the midday temperature is in the mid-70s. That’s warm enough to wear shorts and a tee shirt with no worry of overheating. It might be as humid as it is at home (that would be due to the proximity of the ocean) but it’s so moderate in temperature that it feels comfortable.

In short, the weather is perfect for spending the entire day outdoors. Anything that can be done outside is at its best when done here: Hiking, boating, swimming, cycling…

…and gardening.

It turns out that there are many lush gardens in Maine. Most of the houses we’ve seen have a plot of vegetables or flowers—or both—in their yards. And a garden center near our hotel is one of the biggest I’ve seen anywhere, with an astonishingly diverse assortment of growing things. Who would have expected it?

Not me. I always thought that with its short growing season and cold, icy winters that Maine would not be ideal for gardening. The climate (I figured) might be suitable for evergreens and chrysanthemums but not tomatoes.

What I failed to consider is that although the growing season may be short, the growing day is long. Sixteen hours of sunlight per day, it appears, more than makes up for the loss of May and September.

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This year, I am determined not to lose the battle against powdery mildew.

It’s probably a futile goal—quixotic, really—because we have suffered it every year that we’ve kept the vegetable garden, starting in 2011. Spores of Erysiphe cichoracearum, the fungus responsible for powdery mildew in cucurbits, are present, brought here from elsewhere by the wind (most likely) or by spontaneous manifestation (not likely but it is easy to understand why people once believed in it).

Sadly, the fungus is well-suited to survival and produces resting spores called chasmothecia (all of this is according to the folks at UC Davis; see “UC IPM Online”) that can—and do—resist the freezing weather that kills off weaker organism over winter. The only way to eradicate it is with fungicide, the most effective of which I have no interest in using.

No, eradication is not the answer; management is. And the key to management of powdery mildew is anticipation and early detection. It will appear—that’s inevitable—so I must be ready for it. And that means starting to spray the leaves of the cucurbits, which in our garden are the cucumbers and squash, with a preventative solution and starting to spray them now.

Last year, I found a good recipe on Late Bloomer’s website (see “Late Bloomer – National Heirloom Expo 2013 – Episode 36”; there is other interesting stuff there) and I mixed up a batch today. It’s a simple concoction of water, baking soda, hydrogen peroxide, and dish detergent (which I suspect is there to help the solution adhere to the plant).

I made a loop through the garden this afternoon, spraying each cucumber and squash leaf as I passed. My intuition tells me that spraying while the garden is in direct sunlight is preferable because the sun will evaporate the water, leaving the NaHCO3 and H2O2 (I have no idea what is the chemical formula for dish detergent but it’s probably too long to fit) behind to coat the leaves and inhibit fungal growth.

For the remainder of the season, especially in the fall when the humidity of summer remains but the nights are cooler, I will have to re-spray on a weekly (or so) basis.

Maybe I can’t win the battle but perhaps if I am diligent, I (and the cucurbits) won’t be routed.

The string beans weren’t the only plants that got pulled out this weekend.

The tomatoes, about which I have been obsessing lately, have not been improving despite my pruning of several days ago (see September 27, 2013).  Once infected with late blight (the suspected culprit), the plants have little hope of recovery without the use of fungicides.  Late blight is caused by oomycetes, non-photosynthetic fungi (perhaps that’s redundant?) that spread through the production of millions of oospores.  Oomycete is a cool word but it is a very uncool organism.

I have read about using a baking soda spray in several publications and websites (see, for instance, Late Bloomer’s Episode 2.16) and will probably try that next year, starting early in the season to prevent onset.  We’ll plant the tomatoes in the west planter—the best we can do, in terms of crop rotation—and keep everything as clean as possible.  However, given the ease with which the oospores spread and their ability to survive, underground, through severe weather, we are at a disadvantage (and greatly outnumbered).

It’s much too late for any kind of spray this year so I pulled out the spindly vines of the Sungold, Black Cherry, Brandywine (red and yellow) and Aunt Ruby’s German Green tomatoes that remained.  There were plenty of green (i.e., unripe) tomatoes but none that were fit to eat.  On all of the plants suffering from blight, the disease had spread to the fruit.  I don’t mind a rotten spot or two or even the occasional wormhole or bird peck, but the brown lesions, with their white spore sites, make even the best looking tomato unappetizing.

I’m happy to say that the plants were otherwise healthy and had produced extensive root systems (which required a fair amount of effort to pull out).  I was also pleased (and surprised) to see that the Country Taste Beefsteak tomato vines continue to resist the late blight; there were no signs of the lesions or brown spots on the leaves or stems.  This makes them a very good candidate for next year’s garden.

Of course, they are suffering from something else, possibly Septoria leaf spot (my hypothesis is based on review of photos of afflicted plants online) or maybe early blight.  Unfortunately, all of these conditions are spread by spores, the production of which is favored by the cool, humid weather that occurs in the fall.  I left the beefsteaks alone (well, I may have trimmed a few branches) in the hope that we will be able to harvest the dozen or so ripening tomatoes that are still on the vine.

Warning:  Insect photo below.

Fall returned this week, like an old friend who had been away visiting others for a few months (family in the southern hemisphere, I believe).  It is good to see the autumn come around again and bittersweet to watch as our houseguest, summer, packs up and leaves.  We had some good times these past three months but we’ll have more fun with a different crowd in the months ahead.

The changing season gives me a warm feeling, even while the weather is turning decidedly cooler.  On the one hand, a swim in the pool has almost suddenly lost its appeal (time to close it soon) and I can actually wear long trousers, having faced up to the possibility a week ago.  In the morning, I need a sweatshirt when I go out for a run.

On the other hand, sleeping is much more comfortable.  The air is crisper—although not yet as dry as it will be in winter—and warms up by late morning.  It can be almost as hot as in summer, in an absolute sense, but the heat is usually moderated by cool breezes.  The sun is lower and shade is more plentiful; it provides a handy respite from the still-intense rays of light.  All things considered, this a good time to be outdoors.

Unless you are a vegetable.  Many of the plants have withered away, leaving only bare spots behind.  I’ve already mentioned the shortening day and increasing solar screening by adjacent trees (see August 25, 2013).  Now, with overnight temperatures dropping into the 50s and 60s, the vegetables’ growth rate has slowed to a crawl.  The tomatoes, green beans and squash are still producing but not as much and not as often.

The vegetables are starting to miss their summer companion and will soon be joining its exodus from the garden.

After an unusually warm July, we’ve been experiencing a strangely cool August.  It is great for sleeping (no need to run the air conditioner) but it is not so good for the garden.  The humidity remains high (unavoidable in the northeast in summer) and, consequently, there is a heavy dew every morning.

Anyone growing cucurbits (squash, cucumbers, melons) knows that these conditions are conducive to powdery mildew.  And the evidence in our garden is proof.  The leaves of all of the squash plants—summer and winter—are covered with the white fuzz.  It seems to be increasing daily, almost as I watch, despite periodic (but, admittedly, infrequent) milk sprays.

Luckily (and so far, so good), the mildew has not affected squash production significantly.  New leaf growth is still quite strong, there are plenty of blossoms and the pollinators have not been interrupted.  We will still be eating squash for a few weeks (at least) to come.

Where powdery mildew seems to have the greatest negative impact is on the older end of the vine, nearest the roots.  This portion of the vine has already produced fruit and its leaves would be dying back anyway.  However, the mildew seems to speed up the process.  The question has now become, will the rate of mildew progress overtake the vine’s growth?

I got what I asked for (see June 25, 2013) and summer arrived in spades on the Fourth of July.  We’ve had mostly 90-degree days ever since.  The humidity is high and it rarely gets below the 70s at night so almost needless to say, our pool—and our one small air conditioner—are getting a lot of use.

We’re a bit exhausted but the vegetables seem to be enjoying it.  The tomatoes, peppers and eggplant are all heat lovers and are growing by leaps and bounds.  The squash and cucumbers are also looking pleased with the warmer weather.  We have not had any rain to speak of so I have been careful to run the water every day (the remaining heads of lettuce get a mid-day sprinkling as well) to keep anything from drying out.

Not everything is responding well to the heat, however.  The arugula has been struggling to get beyond the seedling stage even with frequent watering.  And some of the carrots and beets have been in the ground since April.  The carrots in particular are looking a bit scraggly and are probably in danger of bolting.  So we decided to pull out all but the last row of carrots and turnips.

We were not surprised to find the turnips large and meaty—they have been performing well all season—but we were positively ecstatic to discover that the carrots had quietly grown to normal size.  We planted a mixture of seeds that were marketed as a rainbow of colors but comprised only red, orange and yellow, the Roy in Roy G. Biv (I guess that puts us on a first name basis with the rainbow).  Of these, the red grew the largest (and sweetest).

In the space left behind, we transplanted a six-pack of cauliflower seedlings that we purchased a week or two ago from a small, family-owned garden center nearby.  Of the Bishop variety, the seedlings have been toughing it out in their plastic container waiting for an opening in the garden.  We arranged them in a staggered row, loosened their root balls and buried them up to their first set of leaves (their stems had gotten quite long).  These are the only vegetables we did not start from seed and it will be fun to compare the outsiders’ progress to that of the natives.

Between uprooting and planting, we noticed that something has been getting into the basil and nibbling on the leaves.  I can’t say I blame whoever is responsible—the basil is incredibly lush and irresistibly fragrant—but I will say that they are not very tidy.  Several of the basil leaves are covered with scat (frass might be a more appropriate term).  We clipped and discarded the affected leaves and reminded ourselves to carefully wash whatever basil we use.

When the weather flips suddenly from cold and rainy (we had to turn on the heat last Friday!) to hot and humid (more like what we expect in August), it makes watering difficult.

On the one hand, plants like tomatoes enjoy the warmth but they do not like to be overwatered.  At the other end of the spectrum, lettuces prefer moist conditions but will wither in the heat.

It reminds me that I have to pay close attention.  Automatic watering will probably not be sufficient and manual irrigation—the good old watering can—might be needed.

It was downright cold this morning—the temperature dropped to 50 degrees overnight—and yet it will be 85 degrees this afternoon.  These diurnal temperature swings are hard on the system.  When we get into bed at night, we push away the covers and need a fan blowing to keep us cool.  By morning, however, we find ourselves clutching the sheets to our chins while the cats snuggle closer to us for warmth.

At the same time, the humidity remains quite high (possibly worse than in the middle of the summer) and when combined with the cool nights, there is a lot of dew in the morning.  These conditions are conducive to powdery mildew and, if fact, the zucchini plant is now almost entirely covered with it.  After reading up online and watching Late Bloomer‘s “Zucchini Madness – Episode 17”, I decided to try the dairy cure.

Apparently, there are natural antibiotics in milk which have no effect on us (or baby cows) but which are toxic to powdery mildew.  We did not have any milk on hand (we rarely drink it) but there was a bit of leftover cream in the refrigerator.  I had read that the fat content has no effect (non-fat milk could be used) so I diluted the cream with lots of water (too much milk can cause a different form of mold to grow) and sprayed it on the zucchini leaves and stems.  Because of the higher fat content, the mixture produced the distinctively nutty aroma of dairy which was not unpleasant (I’ll see how I feel about it after it has cooked in the sun awhile).

Moving to the other side of the planter, I had thought that we had bacterial wilt of the cucumbers but when taking a closer look at them and tracing the vines with dried, wilted leaves to the ground, I think instead that it is a simply a case of just plain wilt.  The cucumber plants have been in the garden for four months now and their older parts are literally exhausted.  I think I would be too if I had spent a third of a year outdoors.

The leaves have completely dried out—they are crackly and brittle—and the stems have shrunken so much that they look and feel like bundling twine.  I generally avoid pruning cucumbers (because they are susceptible to bacterial infections) but decided that cutting off the dead leaves was worth the risk if it meant that the remaining vines would have a better chance of producing some late-season fruit.

For each plant, I followed the branches from their tips to the ground, snipping off the dead leaves as I progressed.  Some of the vines are still green at their leading ends and are producing blossoms, even though their lower portions are yellow and dead-looking.  On the other end of the spectrum, two of the vines were shriveled and dry along their entire length; these cucumbers are done.  I pulled them out to make more room for those that remain.  When I was done, I had a large pile of debris.

One of the cucumber vines I pulled out still carried a yellowed and partially-formed cucumber.  Despite its color, it looked edible so I washed and ate it.  The cucumber had retained its subtle melon-like flavor but its texture was closer to that of a dried apple.  A bit strange but a nice snack nonetheless.