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Bob Morris

Bob Morris

Bob Morris is a horticulture expert living in Las Vegas and professor emeritus for the University of Nevada. Visit his blog at xtremehorticulture.blogspot.com. Send questions to Extremehort@aol.com.

Standard-sized apple tree cannot be pruned to dwarf size

Standard-sized apple trees may grow to 35 or 40 feet in height. You might be able to keep a standard-sized tree under 20 feet tall through pruning, but the standard-sized apple tree is just too vigorous for pruning to short heights.

Rainy conditions can cause diseases in plants

A disease called fire blight might pop up in some pear and apple trees beginning around May. It can be common several weeks after spring rains, particularly if trees were flowering. It can lead to tree death if not controlled when it’s first seen.

Delay grape pruning as long as possible

Delay pruning grapes as long as possible in the spring to reduce disease possibilities and avoid any late spring frost damage after pruning. Immediately after pruning grapes, consider applying a fungicide to the vines if there were problems with grape bunch diseases last year.

Mexican petunia needs to be contained to area

My experience with Mexican petunia is that it grows like a weed, and I consider it the broadleaf version of Bermuda grass, aka devil grass. If it’s contained in an area and prevented from spreading into the landscape, I think it will be OK.

Check for borers after rainfall

An infrequent desert rain is not a problem. But when irrigation water is applied over and over to a soil that is normally dry, these soils shift, collapse and chemically change. In urban landscapes, this can be potentially destructive.

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Sanitize blades of loppers, hand shears before using

When preparing to prune plants, follow these three rules: adjusting loppers or hand shears so they don’t rip plants instead of cutting them, making sure the blade is sharp for the same reason and sanitizing the blades.

Olive tree will outgrow container so plant in ground

Desert willow can look shaggy during the winter because of the brown seedpods that hang from the tree. The seedpods provide a good supply of birdseed for various desert birds during the fall and winter months.

Verticillium wilt cause death of single branch

Verticillium wilt disease plugs the internal tubes that carry water from a tree’s roots to the leaves. It commonly infects a single branch, causing it to die and appear like it is not getting enough water.

Citrus plants have different tolerances to winter cold

There are two strikes against citrus growing well in the Mojave Desert. The first is their variable tolerance to freezing temperatures during the winter. The second strike is that oftentimes citrus trees flower in early spring when very light freezing temperatures are possible. Tolerance to these freezing temperatures is practically nil.

Control whiteflies as soon as you see them

Whiteflies are a bad insect problem for any plant. Their populations grow so quickly that small numbers lead to large numbers very fast. For that reason, it’s important to get them under control early, as soon as you see them.

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