COMPOST TEA: SNAKE OIL OR ELIXIR? BLACK CURRANTS…
Tea For Plants?
Has your garden had its tea this morning? Tea is all the rage for plants and soils these days. Compost tea. And not just any old compost tea, but tea you steep in water that’s aerated just like an aquarium.
Compost tea steeped the old way, by hanging a burlap sack of compost in a bucket of water for a few days, was one way to provide a liquid feed to plants. The liquid feed wasn’t particularly rich but did provide a wide range of nutrients that leached from the compost, and was convenient for feeding potted plants.
The new, aerated compost teas are billed as an efficient way to transfer beneficial microorganisms from compost into the soil or onto plant leaves. After all, spraying a little tea is less work than pitchforking tons of compost. In the soil, the little guys can spread their goodness, fighting off plant diseases and generally making plants healthier. Or so goes the logic and the promotional material.
Aerated compost tea (ACT) is big business these days, with people selling compost tea, compost tea brewers, and services for testing compost teas. Compost tea is more than big business; it’s bordering on religion (as anyone who criticizes compost tea soon finds out).
In fact, aerated compost tea is not the panacea it’s trumped up to be. Many independent studies have found the tea to be of no benefit, or even detrimental. Occasionally, human pathogens have been found lurking in compost tea.
In The Interest Of Science
I have a friend who believes in compost tea, so in the interest of science I agreed, on his urging, to try it out. To make sure any lack of efficacy could not be blamed on the tea itself, he sent me some compost, a brewer, and instructions for brewing and application. Interestingly, he told me not to try it out in my vegetable garden, because my garden was “too organic”(!)
Long story short: I applied tea to my lawn and to some vegetables in a relatively poor soil at a local farm, and the result was . . . (drum roll) . . . nothing, nada, rien, zip.
Tea Doesn’t Make Sense
All the buzz about compost tea bypasses the fundamental question of why compost tea would limit plant disease when sprayed on plant leaves? The theory goes that the good microorganisms colonize leaves to displace and/or fight off the bad guys.
Compost tea contains some of the microorganisms from the compost that made the tea. These microorganisms are normally found in soils and, of course, composts. But why, evolutionarily speaking, would these microorganisms provide any benefit on plant leaves, for disease control or any other purpose? Furthermore, these microorganisms evolved in a dark, nutrient and moisture rich environment. Why would they survive on a sunny, dry, nutrient poor leaf? The same goes for soils: If the soil has the right environment for a particular set of microorganisms, they generally are there; apply microorganisms to a soil lacking the needed environment and those microorganisms cannot survive.
Occasional research papers report positive effects of compost tea for thwarting plant diseases. I contend that if you spray just about anything on a plant leaf and measure enough plants closely enough, you’ll turn up some measurable response to the spray. That response might be very transitory and very small, but, with the right equipment or instrumentation, you’ll measure some effect. Whether that effect is of biological or practical significance is another story.
With that, I suggest someone begin a series of experiments to see the effect on plant diseases of spraying — say — milk solutions on plant leaves. Wait! A web search tells me that milk sprays have been tested and are, in fact, effective in controlling plant viruses, powdery mildew, and other diseases. In contrast to compost tea, which provides microorganisms but little of the food they need to survive, milk provides a smorgasbord of nutrients to whatever microorganisms tag along for the ride.
On the basis of the evidence, I’d go with milk rather than tea for my plants. And I’ll take my milk without tea.
Black Currants, Mmmmm
Moving on to something noncontroversial, my first black currants of the season ripened June 26th this year. Come to think of it, black currants may not be noncontroversial. Black currants have a strong, very
Belaruskaja black currants
distinctive flavor, loved by some people, abhorred by others. The flavor starts out refreshingly tart as your teeth break the skin and then becomes sweeter and cooling, with a rich, resiny flavor, as you continue.
I count myself among the lovers of black currants, right up there
with blueberries in my book. Black currants earned a whole chapter in my book, Uncommon Fruits for Every Garden. Although humans are divided on whether or not they enjoy fresh black currants, pretty much everyone loves the fruit concocted into jams and baked goods. They also flavor the liqueur cassis, I’ve used them to flavor beer.
Let’s be clear about the fruit in question. Black currants are not the same fruit as “dried currants.” Those currants are raisins made from dried Black Corinthe grapes, a name which was bastardized to “black currant.”
Black currants are borne on medium-sized bushes whose leaves, when brushed against, emit a strong, also resiny aroma. The leaves are sometimes brewed into tea — for humans, not plants.
GOOD FUNGI, BAD WEEDS
Myco . . . What?
There’s a fungus among us. Actually, fungi, all over the place. Right now, though, I’m focussed on a special group of fungi, a group that, as I look out the window on my garden, the meadow, and the forest, has infected almost every plant I see. Like so many microorganisms — most, in fact — these fungi are beneficial.
The fungi are called mycorrhizal fungi; they have a symbiotic relationship with plants. (“Mycorrhizae” comes from the Greek “myco,” meaning fungus, and “rhiza,” meaning root.) The plant and the fungus have an agreement: The plant offers the fungus carbohydrates which it makes from sunlight, carbon dioxide, and water; in exchange, the fungus infects plant roots and then spreads the other ends of its thread-like hyphae throughout the soil to act to be virtual extensions of the roots. The plant ends up garnering more mineral nutrients from the soil. The fungus also helps offer protection against pests and drought. It’s an arrangement that has worked for eons.
Except for where soil has been doused with heavy doses of pesticides or discombobulated by land excavation, mycorrhizae are everywhere. Only a few plant families get along without this symbiosis. Some more familiar, nonmycorrhizal plants include cabbage and its kin, carnations, lamb’s-quarters, and sedums. Other plants can grow without mycorrhizae, but then miss out on some of the benefits and don’t make most efficient use of minerals soil has to offer.
Why mention mycorrhiza at this moment of time? Two books on mycorrhiza were published this year; either one, but not both, are worth reading. Both cover the kinds of mycorrhizae, their effects, their nurturing, and probably everything else you might want to know about this symbiosis. 
Michael Phillips’ Mycorrhizal Planet will appeal more to the hip gardener, the one who burns wood for biochar for their soil, builds hugelkultur mounds (look it up), and spritzes plants with herbal extracts to boost their immune function. He’s mostly right when writing about mycorrhizae but often enters the land of woo-woo when venturing off-track. For instance, he writes, and then runs with, “many species of insects lack the digestive enzymes needed to break down complete proteins.” Not true.
The other book about mycorrhizae, Jeff Lowenfels’ Teaming with Fungi, presents a similar overview to mycorrhizal fungi, and their application, to that presented in Mycorrhizal Planet, with one notable difference. Teaming with Fungi details straightforward methods how you or I can actually grow our own mycorrhizae with which to inoculate plants to get them off to the best possible start.
The two books differ dramatically in their writing style. I eventually tired of Phillips’ overly flowery style and anthropomorphizing. “The synergy that unfolds as a result of outrageous diversity in the orchard delights me to no end . . . .The root systems of fast-growing tree with relatively pliable wood make barter possible between AM [arbuscular mycorrhize] and EM [ectomycorrhizae] fungi.” Lowenfels’ Teaming with Fungi is more firmly grounded in real science and application than Mycorrhizal Planet. I found Lowenfels’ writing more straightforward and engaging: “Some trees form AM, but others have evolved over time and are hosts to EM. Some trees are hosts to both forms of mycorrhizae, though usually at different periods in their lives.” (Different strokes for different folks.)
The mycorrhizal symbiosis was first studied and described in the latter half of the 19th century. Less long ago, but still long ago, I studied them as part of my doctoral work, specifically the ericoid mycorrhizae that are specific to blueberry plants and their kin. With the increased appreciation of the diversity, extent, and effect of the living world within the soil in recent years, mycorrhizae have moved into the spotlight. Read about them, nurture them, and make use of them.
And Weeds Among Us
Rising now to see what’s going on aboveground, I see that the garden has moved mostly into its maintenance phase for the season. That entails mowing, scything, making compost, keeping an eye out for pests and taking action, if necessary.
And, of course, weeding. My weeding weapons of choice are my hands, for larger interlopers, and either the winged weeder hoe or wire hoe for small ones. Called into action weekly, either of the two hoes easily slice through the top quarter inch of soil surface to do in small weeds that haven’t even yet poked their heads above ground. 
All the better to forestall the appearance of large weeds, which are much harder to kill and also threaten to spread seeds or grow strong roots. Regular hoeing also keeps the soil surface loose to better absorb rainfall.
Early July seems to be when true gardeners part ways with other gardeners. Regular weeding and other garden maintenance keeps the garden in good shape for the fall garden which, with good maintenance and planning, is like having a whole other garden, providing vegetables and flowers well into fall.
BLACKCAPS AND PRUNING
Blackcaps All Season (Almost)
It’s a bumper year for blackcaps (also know as black raspberries or, botanically, Rubus occidentalis), at least here on the farmden. Up to last year, we harvested wild blackcaps from plants that pop up at the edges of woods. The current bountiful harvest is from blackcaps that I planted a couple of years ago. Last year’s harvest was unimpressive because the plants were still settling into their new home.
Most blackcaps, like many other bramble fruits, have biennial canes that grow stems and leaves their first year, fruit in early summer of their second year, then die back to the ground. (Annual harvests are possible because while those second year canes are fruiting and then dying, the perennial roots are pushing up new canes, which will bear the following year.)
Niwot and Ohio’s Treasure, the two varieties I planted, stand out from the crowd in bearing on new, growing canes as well as on two-year-old canes. Their two-year-old canes, like those of run-of-the-mill blackcaps, bear now, in early summer. Berries are borne on new, growing canes towards the end of the growing season, until stopped by cold. The next season’s summer crop is borne lower down on those same canes. The upshot of all this is that I get to eat fresh blackcaps in early summer and then again in late summer.
I knew I could expect two crops each season from these varieties when I planted them. That’s why I planted them. What I didn’t know is how abundant and flavorful the berries would be. Unfortunately, for the purposes of evaluation, the two varieties are growing in separate locations that differ markedly from each other. The one in the better location — a humus-rich soil basking in abundant sunlight — yields oodles of large berries. The other variety — planted in a weedy bed shaded from the east by a greenhouse wall — yields less and smaller berries, with perhaps a tad better flavor.
Pruning Recipes
Pruning Niwot and Ohio’s Treasure is as important for ease of picking and pest control as it is for other brambles. And it’s easy.
Right after the current crop grinds to a halt, I’ll cut every cane that bore fruit right to the ground. These two-year-old canes are going to be starting to die anyway. I could cut them down in winter, but cutting them sooner gets the thorny canes out of the way of late summer harvest.
All summer long, I’ll also pinch out the growing tip of any new canes when they reach about four feet in height. Pinching induces side shoots, on which fruits are borne.
That’s it for summer pruning. Sometime next winter I’ll reduce each clump of canes to the six healthiest and shorten each side shoot on remaining canes to about 18 inches long.
All in all, Niwot and Ohio’s Treasure yield a lot of delicious fruit over a long period of time for minimal effort. Now, if only the canes were thornless.
And More Pruning
Whoa, I can’t yet put away the pruning shears. I need the shears for some rose bushes. With the rose “crop” subsided, pruning will get varieties that bear only in June ready for next season, and those that bear again and again through summer to bear again and again.
For roses that bear only once each season, such as the heavenly scented Rose D’Ipsahan, or the cheery, lemon-colored blossoming Father Hugo’s Rose, I cut back some very old stems right to or near ground level, and shorten the remaining stems, some by a quarter of their length, others by three quarters of their length. Then I go over the bush to thin out any crowded stems. This pruning makes room for and stimulates growth of new shoots with ample time for them to initiate flower buds this summer that will unfold next spring.
Repeat blooming roses get pruned differently. The goal is to cut off stems with spent flowers and coax new growth that will flower this season. Instructions for pruning hybrid tea roses are very specific; and I quote: “. . . . cut the stem back to a five-leaflet leaf. Retain at least two five-leaflet leaves on each shoot.”
I don’t grow hybrid teas, which generally are finicky roses, preferring tougher roses such as some of the David Austin varieties, such as L. D. Braithewaite
Braithewaite rose
and Charlotte. Pruning is very simple. I just lop stems or groups of stems laden with spent blossoms as far back as I feel like to keep the shrubs from growing too large. They both get another pruning in late winter.
Another rose I grow, rugosa rose, won’t get any pruning this summer. Besides its nonstop, fragrant flowers, rugosa rose also bears nice hips, that is, fruits. The hips make excellent jam and are rich in vitamin C. Pruning in summer would remove spent flowers which then couldn’t go on to swell into fat hips.
