Tomlinson: Keeping plants wet helps prevent disease, insects

It is the end of a hot, dry summer. Unless plants have been watered weekly throughout the growing season, they are stressed by the heat and lack of moisture. As a result flowering and fruiting times are; often early or late. Usually at this time of year gardeners reduce the amount they water encouraging plants to head into dormancy but because of the dry conditions, continue watering. Water once a week providing enough moisture for the plant to sustain itself as well as gather nutrients for dormancy.

Leave the sprinkler or soaker hose running long enough to provide about an inch of water. The water output is dependent on water pressure and the sprinkle used but it usually averages to about an hour. If in doubt, put a rain gauge in the path of the sprinkler. Watering early in the morning or late at night is preferable as less water evaporates. If watering during the hottest part of the day, keep the water running long enough that the plants cool down and the leaves do not burn.

Annuals and vegetable gardens that have not received enough moisture are stunted. The shortage of moisture is very visible in heat seeking plants such as squash. If the plants and fruit are small, chances are they have not received enough moisture. Watering and fertilizing the plants now can improve the growth of the plants and produce unless the weather changes and there is a hard frost.

Trees and shrubs have huge root systems allowing them to draw from a large area and hold massive amounts of moisture but their supplies can be depleted. The majority of their feeder roots are in the top 12 inches (30 cm) of soil located in and around the dripline or outermost branches of the plant. Placing sprinkles or soaker hoses in this area will provide roots with much needed moisture.

Stressed plants are more susceptible to insects and diseases. One sign that a tree is not well are having a number of holes drilled by woodpeckers. While it looks like a woodpecker kills trees, they are opportunists that seek out stressed or sick trees as their sap is more palatable.

Dead or wilting leaves are a sure sign that a plant is not healthy. In a tree it could mean a broken branch or it could be an infection such as black knot or fireblight.

Black knot is prevalent in May Day trees in Alberta. The disease is easily recognized as infected wood is enlarged and black. As the disease progresses it blocks the plants cells that transport food and nutrients throughout the plant. Branches on the wrong side of the knot starve and die.

Fireblight is a bacterial infection that spreads rapidly and can wipe out an entire orchard in a season. Dead leaves that do not fall off the branch, blossoms that turn brown, dark scorched looking wood, or oozing bark are all symptoms that the plant has fireblight.

When an infection is discovered it should be removed immediately. Whenever possible, cut into healthy wood under the infected area. Double bag the infected wood and place it in the garbage. Do not keep it for firewood or put it in the chipping pile. Infected wood that is saved, still has the ability to infect other trees.

Keeping plants healthy is the first step to prevent the spread of disease. The second is to work together with neighbors to remove infected branches or trees limiting the spread of a disease or bacteria.

Linda Tomlinson is a horticulturalist that lives near Rocky Mountain House. She can be reached

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