Hollyhock rust, West Nile precautions, other reminders

[June 02, 2011]  Rust on hollyhocks -- Hollyhocks are one of the traditional, old-fashioned flowers often grown in our area. This year, they are definitely interesting. Even before the flowers open. Most area hollyhocks are infected with rust. Rust is usually a spring and fall disease problem, when it occurs.

Rust first shows up on the bottom of the lower leaves, and the top side of the leaves develops some rather striking bright yellow to orange spots. Rust can attack all plant parts, including leaves, stems and leaf petioles.

The rust disease spends the winter in old plant parts on the ground. Removal of the plant material will help reduce infection possibilities. Increasing air flow and reducing humidity will also help. Control is best accomplished by removing infected leaves at the first sign of the rust (on the bottom of the leaves). Chemical control may be needed, and sprays containing sulfur are effective.

West Nile virus

West Nile virus has, unfortunately, become a household phrase. WNV was first isolated in Uganda, Africa. It can harm humans, birds and other animals. It is transmitted by infected mosquitoes, primarily the northern house mosquito. The mosquito becomes infected after biting wild birds that are the primary host of the virus. The mosquito is actually able to transmit the virus after 10-14 days after biting the infected bird.

The mosquito life cycle has four stages: egg, larva, pupa and adult. The female mosquito lays eggs on water or moist soil. Most of the larvae hatch after 48 hours, and the larvae and pupae live in the water. The females need a blood meal before they can lay eggs, so only the females bite. They bite every few days during their adult lives, which may last several weeks.

Preventing mosquitoes is a first step. Homeowners can best accomplish this by eliminating standing water. Tires and old containers are obvious places to start. Drill holes in the bottom of recycling containers, clean clogged gutters, don't allow stagnant water in anything such as birdbaths, change landscape slopes to eliminate standing water, and use larvacides in standing water that can't be eliminated. Bt Israeli is the strain that is effective against mosquito larvae -- not the Bt variety commonly used on trees and gardens! The mosquitoes have already begun hatching, so treatment time is at hand.

Also protect yourself from bites. Mosquitoes can travel up to three miles from their breeding sites! Make sure that screens and doors are tight; use proper outside lighting such as fluorescent lights; stay indoors at dawn and dusk when mosquitoes are most active; wear long-sleeved shirt and long pants when you must go outside; and use insect repellents properly applied. Exposed skin should be sparingly treated with a repellent containing up to 30 percent DEET (up to 10 percent for children), and make sure to treat thin clothing as well (since mosquitoes can bite through thin clothing).

Reminders

We are now in the middle of the correct planting time for the warm-loving vegetables for our gardens. This would include lima beans, cucumbers, eggplant, melons, peppers, summer squash, winter squash and pumpkins. Pumpkins for use as fall ornamentals should be planted around Father's Day so they have less chance of rotting before fall display. Believe it or not, we're at the proper timing for fall garden plantings. That means potatoes, kale and some others. Some of the planting dates overlap this time of year. That basically means plant it, but you can expect harvest to be closer to fall.

Keep pruning flowering shrubs after they complete their blooming. That will allow for more flower buds for next year. Coming up the end of June will be the pruning time for evergreens.

Bagworm spray time will be coming up in mid-June. We'll try to fine-tune the date as we get closer. The cool spring has delayed things to this point, but the current hot weather could catch us back up to the book timing of June 15.

[By JOHN FULTON, University of Illinois Extension]