Good Gardening

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University of Illinois Extension
Good Gardening

June/July 2006

Rejuvenate 'Tired' Plants

By mid-summer it is common to see some of our perennials looking a little ragged. Consider cutting these plants back to encourage a flush of new growth. The plant may not flower again, but at least it will look green and fresh instead of brown and tattered. Cut plants back based on how they look. Some perennials may need just a trim, while others may need to be cut back all the way. Be sure to follow up with watering to encourage that flush of new growth to develop. Dry plants don't grow much.

Garden tidbits:

  • If you pinch your mums to make them fuller, stop doing so by mid July so the plant can start forming flower buds for fall.
  • When bearded irises are finished blooming, think about dividing them if they need it. Dividing after bloom time allows you to inspect the rhizome for borers and bacterial soft rot.
  • Keep deadheading annual flowers to encourage them to bloom all season long.

Orange Lawn?

As July approaches be watching your lawn carefully. Often in mid-summer we see orange spores on the lawn (you see them best when you walk across the lawn in white shoes). This is a sign of rust disease, which commonly occurs when the lawn is growing slowly due to the heat and dryness of summer. The damage to the lawn is usually minimal and it seldom needs chemical control. Some watering and an application of nitrogen fertilizer will get the lawn growing enough to overcome the disease.

Japanese Beetles

As mid-summer arrives, so do the Japanese beetles. These beautiful insects are iridescent green in the front, with copper colored wings in the back. Although beautiful, they are also quite damaging. They will chew leaves, often leaving the veins, so that the leaf has an almost lacy appearance.

Japanese beetles are equal opportunity feeders. They feed on about 400 different species of plants. They love roses and anything in the grape family. Their young (grubs) will feed on the roots of the lawn.

This insect can be very difficult to control. If the population is small, you can try hand picking them. For larger population you may need an insecticide. Don't spray the whole yard. Instead, decide which plants are truly special to you and treat only those plants. Be wary of using Japanese beetle traps. They are sometimes too effective, drawing in more beetles than they can actually trap and increasing th problems in your yard.

Treat for the grubs, when the new ones hatch out (usually early August). They are small at that time and will more easily be killed by a lawn insecticide.

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Know Your Herbicides (Weed Killers)

There are many herbicides and they don't all do the same thing. Before purchasing an herbicide, it is important to have some information about them.

A pre-emergent herbicide kills weeds as they germinate (sprout) from seeds. Pre-emergent herbicides generally form a barrier against newly germinating seeds. That barrier may be formed by incorporating the product into the soil either manually or by watering it in.

A post emergent herbicide will control existing weeds, but will do nothing to stop new weeds from germinating out of seeds.

A selective herbicide kills certain plants but not others. Herbicides labeled for control of weeds in lawns, for example, will kill broadleaf weeds like dandelions and thistles, but will not kill grasses.

Non-selective herbicides kill or damage all plants. These products can be useful for killing weeds growing along fence rows and in cracks in sidewalks and driveways. Care must be taken when using them in areas where weeds and desirable plants are growing side by side.

Contact herbicides kill only the part of the plant on which they are sprayed. The root system is not killed and the weed may grow back from the roots.

Systemic herbicides are absorbed by the plants and taken into the root system, so the whole plant can be killed.

Mosquitoes in Wetlands?

Contrary to popular belief, healthy, well-functioning wetlands can actually reduce mosquito populations. According to U of I Educator John Church, healthy wetlands provide habitat for many insects and animals including natural enemies of mosquitoes. The predators keep the mosquito population low.

Mosquitoes can become a problem, however, in areas that have standing water that do not support the beneficial predators that feed on mosquitoes. This would include sites such as old tires, birdbaths, and other containers that collect rainwater. Even hollow logs hold water and low spots in the ground can provide spots for water pools. And because these types of places do not provide good homes for beneficial insects and other kinds of wildlife that feed on mosquitoes, the mosquitoes can quickly reproduce.

Keep the Vegetable Patch Going

Do you use a lot of vegetables? If so, you will want to keep your vegetable garden as productive as possible. As summer heats up, the cool season plants like peas and lettuce will stop performing. Pull them out and replace them with warm season crops like tomatoes and beans.

In late July or early August, if some of your warm season crops have been harvested or if the plants are going downhill, pull them out and replant cool season crops for a fall garden. If you plan carefully, you may be able to use the same piece of land for two or three crops.

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