Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: SUNDAY, February 6, 1994 TAG: 9402070273
SECTION: HOME PAGE: D-14 EDITION: METRO
SOURCE: John Arbogast
DATELINE: LENGTH: Medium
A: Yellow sticky traps are effective in luring and catching adult whiteflies. Two excellent sticky substances that can be used to coat those yellow boards are: heavy motor oil (SAE 90), which, by the way, is easy for the gardener to wipe off the yellow boards with trapped whiteflies, and a commercial insect trapping compound from a garden center or hardware store, such as "Tack Trap."
I'm sure you realize that without knowing the culprit that is injuring the plant and whether it is still active, it is impossible to recommend any control or remedy. Since you didn't see the pest that chewed those holes in your rhubarb leaves, I would guess that the culprits were snails or slugs, pests that feed at night when it's cooler and JOHN ARBOGAST gardeners might not see them. Rabbits or other animals who might damage gardens would likely eat whole plants.
So, when you notice new holes being chewed in your rhubarb but can't find who's doing it, go out to the rhubarb patch at night with a flashlight and examine both sides of the leaves. This will allow you to select the proper control as well as know if the enemy is still active. For example, if you do find snails or slugs this spring, they can be controlled with slug bait approved for edible plants if the bait is applied to the ground before the slug population gets out of hand.
Q: Since moving here we have had failures with Cannas. Soil tests done by VPI&SU show the pH in the Canna area to be 5.9. Is that too acid? What is optimum for Cannas? J.Q.A., Daleville
A: Cannas like a pH similar to other annuals, perennials and bulbs. The optimum pH for Cannas may be 6.2 to 6.8. However, even though a pH of 5.9 is acidic, it is not far enough from the ideal range for Cannas to be harmful. I would say that some factor other than soil pH is responsible for your failures with Cannas.
These cultural needs of Cannas must be fulfilled to get good growth: full sun, digging of the bulbs in the fall after frost and winter storage of Canna bulbs at 40 to 50 degrees F, good drainage, moisture during growth and medium amount of nutrients.
Q: I have a hydrangea bush planted on the southeast side of my house that has never bloomed. I have tried this plant at other locations to no avail. The foliage is beautiful and healthy, but no bloom. Help! I've had this plant for 12 years. E.M., Roanoke
A: I've had this question before in my 20 years working for Virginia Cooperative Extension, and it is not easy to answer through the mail. There are many varieties of hydrangeas, and the person from Virginia Tech who helped me answer this question some time ago explained that the flowers of one of the hydrangeas are not showy and may cause the owner to think their plant is not blooming. So, take a leafy branch sample to your local Extension office after the plant leafs out so that it can be sent to Virginia Tech for variety identification. You are served by the Roanoke City Extension Office, 857-7915, in the Jefferson Center, 540 Campbell Ave. SW, Suite 317, in downtown Roanoke.
Pruning at the wrong time can prevent a hydrangea from blooming. Proper variety identification will be necessary to suggest proper pruning.
Send short questions about your lawn, garden, plants or insects to Dear John, c/o the Roanoke Times & World-News, P.O. Box 2491, Roanoke, VA 24010-2491. We need your mail, but this column can't reply to all letters.
Arbogast is the agriculture extension agent for Roanoke
by CNB