Earth Smart's gardening resource blog
Posted: Apr 28 2017
After many years of industry experience, we have compiled some information on various topics for you to get the most out of your gardening experience.
FLYING INSECTS - FLEA BEETLES
Flea beetles are small black flying insects that chew holes in leaves of plants. Typically, adult flea beetles winter in the soil and become active in early spring when new plant growth appears. Plants become less attractive to the beetles as the leaves enlarge and thicken. Generally, damage resulting from flea beetles is cosmetic and their impact on healthy plants is minimal.
Flea beetles can be controlled by:
• Light cultivation
• Adding organic matter in the form of compost, straw, etc. to the soil
• Watering with a mixture of dish soap & water or water alone in full sunlight
• Placing bruised elderberry leaves over the affected plants
• Companion planting using mint as a deterrent
Many plants not only inhibit the seed germination of other plants but their own as well. Experiments by Robert L. Neill and Elroy L. Rice of the university of Oklahoma involving western ragweed show that it is inhibitory to nitrogen fixing algae nitrogen fixing bacteria and nitrifying bacteria.
Field studies indicated a different pattern of vegetation around the ragweed and that these patterns are due neither to mineral nor physical properties of the soil nor to competition. It is the root exudate, leaf lechate and decaying leaves of the ragweed that inhibit many of the early invaders of the abandoned fields.
The root exudates from rye grass and wheat seedlings suppress germination of seeds of field or corn chamomile, the scentless chamomile or corn mayweed. Bean seedlings suppress germination of wheat or flax seeds, Violets suppress germination of wheat seeds.
In some plants the suppressing substances may be formed in the seeds and fruits, in others in the roots, leaves or stems. Essential oils in many herbs and even in trees such as poplar, citrus or the conifers, inhibit the germination of seeds of other plants to varying degrees.
NATURAL INSECT REPELLENTS
NATURAL ORGANIC INSECTICIDES
Garlic can control diseases that damage cucumbers, radishes, spinach, beans and tomatoes.
Onion spray can be used as a natural fumigant.
Saprophytes (tree fungi) can aid trees in resisting bark canker, decay fungi and leaf rust fungi.
Typically, insects are attracted by scent and, as a result, plants can be used as attractants to lure pests away from garden crops. Insects lay their eggs and feed on the attractant plants and garden crops are . Two such attractants are mustard and nasturtium.
Insect repellants can be prepared from citronella, eucalyptus, cedar wood, clove, rose geranium, ginkgo, elder, pyrethrum, lavender, thyme, wintergreen, sassafras, pine tar, etc.
LEAVES ARE THE LUNGS OF PLANTS
In plants, water moves from the root to the leaves via the stem. The water then leaves the xylem in the leaf and evaporates into the atmosphere. Water movement is driven by the evaporation through small pores on the undersides of leaves called stomata. The stomata of a leaf permit the leaf to control evaporative cooling and water loss. This process...
• Cools the the plant
• Moves nutrients up from the root
• Maintains the turgor pressure in cells
Turgor pressure is important for the following reasons:
• It maintains the plant in an upright position so that it can take advantage of light.
• It is important for the functioning of the guard cells, which surround the stomata and regulate water loss and carbon dioxide uptake.
• It is the force that pushes roots through the soil.
Mulch can be almost anything that retards loss of moisture, but organic mulches which add nutrients to the soil are considered the most helpful. These include chopped bark, buckwheat hulls, cocoa shells, coffee grounds, corncobs, cottonseed hulls, cranberry vines, evergreen boughs, grass clippings, hay, hops, leaves (particularly oak leaves which repel slugs, cutworms, and grubs of June bugs) manure, peanut hulls, peat moss, pine needles (great to increase stem strength and flavour of strawberries) poultry litter, salt hay, sawdust, seaweed, stinging nettle, straw, sugar cane residue, tobacco stems and wood chips and shavings.
Why do most annual plants die in the autumn? Larry D. Nooden and Susan L. Schreyer at the University of Michigan are studying a chemical "death signal" possibly a hormone which they have traced to plant seeds. The possibility is being considered that seeds inside mature fruits such as soybean pods send out hormones, which cause plants to yellow and die even before nights cold enough for freezing cut them down.
Gardeners for years have known that if faded flowers are picked before they form seeds the plants will continue to produce more flowers. Pansies are a good example. Among the vegetables okra will continue from early spring to frost if the pods are kept picked before they harden.
Nooden says that this idea was tested on soybeans. Growing pods were plucked from one side of the plant only and allowed to remain on the other. The side with the mature pods and seeds turned yellow and died, the other remained healthy.
Certain weeds indicate a soil rich in potassium. These are march mallow, knapweed, wormwood, opium poppy, fumitory, russian thistle, tansy and sunflower. Red clover, however, is a good indicator of potassium deficiency. It will disappear with increasing acidity.
Tobacco takes up potassium in its leaves and stalks and, as a result, is a good plant for composting provided it has not been sprayed with synthetic chemicals. Vegetables that like potassium are celeriac and leek.
BIOLOGICAL NITROGEN FIXATION
RHIZOBIUM BACTERIA FOR NITROGEN FIXATION & NODULE FORMATION
Of all the mineral nutrients in the soil, nitrogen is generally the most difficult for plants to acquire. Even though nitrogen is the most abundant element in the atmosphere, plants alone, do not have the ability to obtain (fix) it. Only plants, that form a symbiotic relationship with nitrogen fixing bacteria i.e. rhizobia, gram-negative bacilli that invaded the roots of plants, can fix atmospheric nitrogen.
Biological nitrogen fixation is an important factor in any sustainable agriculture program. Biological nitrogen fixation is a process in which nitrogen is taken from its relatively inert molecular form (N2) in the atmosphere and converted into nitrogen compounds useful for building plant protein.
The best known nitrogen fixing plants are legumes i.e. clover which contain symbiotic rhizobia bacteria within nodules in their root systems, producing nitrogen compounds that help to fertilize the soil. The great majority of legumes have this association, but a few genera (e.g. Styphnolobium) do not.
A few dollars worth of rhizobia inoculant can replace hundreds of dollars worth of nitrogen fertilizer and significantly improve soil and crop health.