By Staff Writer Stacey Warde
These are not your typical household ants that invade the kitchen pantry, or crawl up the wall or along the floorboards through a crack in the door.
These are annoying, pesky, field-tested, farm-hearty ants that are making their homes—nests, really—in a few of the 5-gallon container grow bags that hold all 1,500 of our plants.
The bags were suggested as a temporary but reliable means for bringing the plants to maturity, which takes about three years, until we can find a permanent home for them. The farm advisor told us that the bags would be good up to five years.
We’ve run into a number of problems with the bags as the plants reach their three-year mark and begin to outgrow the containers.
One of the more serious problems with the containers is that as the plants mature they begin to use up more moisture and the bags, which sit above ground and exposed to the elements, will quickly dry out. With the recent flush of green leaves and the explosion in blooms and berries, the release of moisture is compounded and some plants showing signs of stress—damaged twiggy stems, cracked berries, shriveled up leaves—and drying up more quickly.
The extensive leaf surface alone on each plant is significant enough to dry out some bags in just one day. The leaves release moisture as they produce sugars for the emerging fruit and play a significant role in the health of the berries.
Add one good day of sun and wind, and the extensive leaf systems “breathe” out more moisture, more rapidly, making it imperative to water the plants regularly, maybe even twice a day in warmer temperatures.
Of course, the best way to solve that problem will be to get the plants into the ground, where moisture, with the right amendments and mulching, is retained more easily, better protects the roots from drying out, and helps reduce overall water output. Obviously, plants in the ground have a lesser risk of drying out, which is an important factor in keeping blueberries healthy.
Unfortunately, that doesn’t seem to be an option for us right now; we’re still seeking the ideal location to put them into the ground, so we’re stuck with the bags. The next best solution, according to our farm advisor, is to transfer the plants into bigger bags.
“You’ll need to start using 15-gallon containers,” he told us recently, when we reported our miseries with thirsty plants and the siege of nesting armies of ants.
I thought back to the several days we spent filling the 5-gallon grow bags, how we moved them with pallets on a forklift because they were too heavy to carry or cart. It’s hard to imagine filling and moving bags three times as large and heavy.
Nonetheless, it’s a job that will need to be done in the near future, probably sometime soon after this year’s harvest, unless we can find a permanent home. Until then, however, I’ll need to closely monitor the smaller bags for moisture and possible infestations of ants or other pests.
Besides posing a major risk to the plants’ need for water, dry bags seem to be a magnet for ants, which have been swarming the bags that are driest, often because of a broken or misplaced emitter. When the emitters fail, it will take a day, or two at the most, for the bag to go dry and the plant to begin showing signs of stress.
Dry, droopy leaves are the first indicators, of course, and usually, underneath the canopy of troubled leaves will be a swarm of ants running around the inside and on top of the bag, as well as along the stems and twigs of the plant.
“Ants also perform many useful functions in the environment, such as feeding on other pests (e.g., fleas, caterpillars, termites), dead insects, and decomposing tissue from dead animals,” according to the University of California’s Integrated Pest Management Program.
Their habit of protecting some insects, however, can have a negative impact.
“On outdoor (and sometimes indoor) plants, ants protect and care for honeydew-producing insects such as aphids, soft scales, whiteflies, and mealy bugs, increasing damage from these pests,” says the UC information sheet.
One telltale sign of ant infestations includes their superhighways, lanes of the pesky insects, that run along the drip lines that feed the plants, and if followed will lead to one or more of the nests they’ve established.
Another telltale sign, which is more noticeable and a much more serious problem, is the presence of scale, a prehistoric-looking insect that imbeds itself into plant stems, and begins to create a colony of armored pests that creep up the length of the stem, secreting sugars, a “honeydew” that the ants feed upon.
As a grower recently informed me, “Ants farm scale. They work together.” It’s a nice symbiotic relationship that isn’t so great for blueberry plants.
The University of Michigan provides the following information on scale: “Scale infestation can cause loss of bush vigor, sooty mold, and blemished fruit. Each scale is a small, waxy dot 2 to 3 mm in diameter, which covers an immobile yellow insect.”
With warmer temperatures, the little “yellow insect” emerges from its prehistoric shell and seeks newer, tender shoots to infect.
Eventually, if left untreated, scale will cause the plant to shrivel up and die. The most effective control, according to most data, is to eliminate the scale by trimming and pruning away the infected stems.
I’ve already severely trimmed at least six or seven plants that have been infected with the scale, which were also infested with ants. So far, we’re fortunate to have avoided the further spread of scale and the treated plants appear to be doing well.
Another way to treat scale is to spray with an oil-based insecticide when the critters emerge from their armored shells as temperatures warm.
For me, it makes better sense to prevent the spread of scale by controlling the ants, which bring the pests with them. It’s a vicious cycle and one that apparently can never be completely controlled.
I’ve been experimenting with a mix of diatomaceous earth and coffee grounds gathered from a local coffee shop. I’m looking for the quickest, easiest, cheapest and least harmful approach that I can find.
I read somewhere that coffee grounds help to deter ants from settling; the DE apparently cuts into the their exoskeletons and causes them to “bleed” to death. I figured that a mix of the two would be like a one-two punch.
It’s not working.
So far, it feels like a losing battle. The ants keep coming back, or they appear elsewhere in the field, as if they’ve rallied for and found a new location. I’ve lost count of how many bags I’ve treated with this mix and I may need to take a different approach.
I’ve begun using bait containers with insecticide in selected areas of the field. I’d love to continue with an organic method, which will always be my first line of defense, and will seek out more options, but I’ll not risk losing the plants.
For now, controlling the pests is like the Sisyphean task of pushing a rock up the hill and watching it roll back down again, but as long as the plants remain healthy and bear good fruit, I’ll consider it a victory of sorts. §