Garden Notes: Pollination

Nature is buzzing with pollinators going from plant to plant.

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Bats and fireflies at dusk mean glorious high summer. Butterflies, lovers of sunlit places and warmth, are more numerous and noticeable now, especially the larger and more spectacular species.

Hot and steamy days have arrived and are putting air conditioners to the test. So have crabgrass, beetles, jellyfish, biting flies, and various other signs (both good and bad) of the seasonal flux.

The current acknowledgement given to the importance of pollinators and their work — even among those who believe “the only good bug is a dead bug!” — is satisfying. The astonishing array of wasps, hornets, and pollinators other than honeybees (hummingbirds) in my home garden makes audible buzzing as they busily pollinate, flutter, and zoom around from flower to flower. In the garden, I want to hear buzzing!

And after pollination?

If a plant reseeds easily, it shows it is attractive to pollinators. Among those that appear in my vegetable garden are cilantro, shizo, dill, gloriosa daisy, Verbena bonariensis, feverfew, foxglove, annual poppies, and radicchio. Also, the many wild plants (i.e. weeds) of the Island excel at attracting pollinators. Treasure them.

After all, plants that appeal to pollinators get pollinated successfully: If they self-sow they attract pollination. Pollination leads to viable seed, seedlings, and more productive food plants. (Not all food plants are insect-pollinated, although important food crops are.)

Widespread spraying is exacerbating the decline of these basic, building-block units of insect life, which leads to further ecological distress. Think twice, and then think again, before ordering up another round of supposedly safe spraying.

Heartbreak tree

Albizia julibrissin, the pink silk tree or mimosa, is often mentioned as a favorite tree and object of plant lust. Indeed, one in full flower, as they are now on the Vineyard, is quite a sight. A small tree studded with fuzzy pink-and-white flowers and with spreading branches and dappled shade, albizia brings the look of the African veldt or other exotic locale to one’s own garden. I describe albizia as the ‘heartbreak tree’ for the following:

The albizia is attractive to pollinators and sets pods in the style of other leguminous trees such as honey locust, which result in seedlings cropping up readily. The trait places albizia at risk of landing on the invasive species list.

Albizia in Wikipedia: “Breeding work is currently underway in the United States to produce ornamental plants which will not set seed and can therefore be planted without risk. However, in the Eastern United States it is generally a short-lived tree, being highly susceptible to mimosa vascular wilt, a fungal disease caused by a species of Fusarium [i.e., sudden death], though the disease does not seem to have seriously impacted its populations. Because of its invasive tendencies and disease susceptibility, it is rarely recommended as an ornamental plant in the U.S., though it is still widely planted in parts of Europe.”

Improved cultivars are becoming available, such as ‘Summer Chocolate’ (red foliage aging to dark bronze, with pale pink flowers) and ‘Ishii Weeping’ (or ‘Pendula’) with a drooping growth habit. To prevent heartbreak, improved cultivars sound like a good idea.

On a slightly different, good-news note, horse chestnut (Aesculus hippocastanum), another wonderful shade tree with heartbreak potential, appears to be doing unusually well on the Island this summer. This is unlike the typical situation.

Usually, horse chestnut suffers from Guignardia leaf blotch, caused by the fungus Guignardia aesculi, where its leaves are highly disfigured by the fungal infection. Why this reprieve may be is beyond my scope; I hope there will be feedback from horse chestnut tree experts.

According to the Connecticut Agricultural Experiment Station “Raking and disposing of fallen leaves will reduce the chance of infection in the following season. Since this disease is usually not a serious problem for the health of the trees, chemical controls are usually not necessary.”  https://portal.ct.gov/CAES/Plant-Pest-Handbook/pphH/Horsechestnut-Buckeye-Aesculus

In the garden

The appearance of fall webworms is yet another signal that the season is wending its way onward. Webworm nests consist of webbing encasing a branch or portion of branch in which numerous larval caterpillars of a small native moth live. Apart from the aesthetics of it, they are usually not a serious problem and nothing needs to be done. However, birds will find the caterpillars if nests are broken open with a pointed object.

Deadhead annuals and cut back re-blooming perennials, such as coreopsis, salvia, monarda, and nepeta, to keep the blooms coming. Sidedress roses with low number, organic soil food. Sow fall crops such as winter squash, brassicas, beets, Swiss chard, and carrots now. Provide shade for lettuce and other crops that dislike hot locations and heated soil. Cure garlic in well ventilated conditions to dry and preserve.

Branches of hydrangeas that are in contact with the ground, looking like vertically growing shrublets, root easily; often these have started to. Look for these and sever to propagate more plants. Pot them in potting soil mixed with perlite and keep well watered.

Take cuttings now to propagate a wide range of plants. Some gardeners, including RHS Advice, recommend pruning out (“stopping”) growing points of eggplant when plants are a little more than a foot tall, to promote branching and better fruit; stake well. Crab grass loves heat; it will be germinating everywhere, including beneath bushy plants in perennial beds.

Plant warfare

Crabgrass is but one of a number of plants that emit allelopathic chemicals through their roots, which can act like herbicides to other kinds of plants. Other examples include members of the Chrysanthemum family (such as daisies) and garlic mustard (Alliaria petiolata). Any plant that is observed creating carpets of itself is likely to employ “plant warfare” against other vegetation.

For further understanding of Allelopathy, link here: agropedia.iitk.ac.in/content/allelopathy. To plan effective planting designs, here is a list (from Google) of common plants that exhibit Allelopathy: cherry laurel; black walnut; bearberry; sumac; rhododendron; elderberry; forsythia; goldenrod, and some ferns.