Summer so far has been rather pleasant. Both heat and humidity have been low. Rain has been sufficient in most parts of the state. The down side to rain is mosquitoes, which emerge as adults about 14 days after a rain.

Typically, July means produce and pests. Hard although it may be, we must remain vigilant about weeds, insects and diseases, and timely harvests of the bounty of our gardens. Early morning is probably the most comfortable time to be out and the best for our plants as well. In the morning, flowers and herbs and leafy greens are well hydrated and will stay fresh longer if cut then.

In the heat of summer, a good layer of organic mulch is a gardener’s best friend. It suppresses weeds and holds moisture thereby reducing the need for weeding and watering. In the vegetable garden use clean straw or hay up to 6 inches deep or a layer of compost 2 – 3 inches deep. Flowers, shrubs and trees can be mulched with a 3 inch layer of woodchips or shredded bark. The only warnings are to avoid mulch in moist, shady spots where slugs and earwigs are a problem and never pile it against the bark of trees and shrubs.

True vigilance is needed to watch for insect, disease and wildlife problems. Find out what the key pests are for each of your plants and watch for signs and symptoms when they are most likely to be present. Early treatment is always more effective. Get help to accurately identify plant problems before making any treatments. In many cases, the damage may look worse than it really is or it may be too late to treat this year anyway. Diagnosing the problem now allows you to plan for prevention for next year.

UW-Extension can help. Each county UW-Extension office in southeastern Wisconsin operates a Horticulture Help Line. Call to talk to UW-Extension staff and volunteers who can discuss your plant problems and provide solutions. The new UW-Extension Horticulture Center located at Boerner Botanical Gardens is now open Monday through Thurday. It is located on the lower level of the Education and Visitor Center at the garden in Whitnall Park in Hales Corners. Hours are Monday and Tuesday from 10:00 a.m. until 6:00 p.m. and Wednesday and Thursday from 11:00 a.m. until 7:00 p.m.

For more local gardening information and links to many other great gardening websites, visit the UW-Extension Horticulture Team website at wihort.uwex.edu. University research-based information is also available from downloadable publications from UW-Extension at learningstore.uwex.edu.

Numbers in parenthesis after a garden calendar entry are for UW-Extension InfoSource messages. InfoSource is an on-line service where you can search for the 3 digit topic number provided and read a brief but succinct script with the basic information on the topic. View and download scripts for these messages at infosource.uwex.edu.
 

First Week

Watch the leaves of your tomato plants for signs of leaf spot
diseases. The most common, septoria and early blight, appear first on lower leaves and can be effectively controlled if leaves are removed as soon as leaf spots are seen. If it has gotten away from you, chemical control is also possible with a fungicide containing chlorothalonil.


To prevent bacterial wilt of squashes, melons, cucumbers, and gourds, apply
rotenone or carbaryl (Sevin) as a dust if either striped or spotted cucumber beetles are present. Dust late in the day after flowers have closed and bees are no longer active. Plants already infected with the wilt should be removed and destroyed immediately.


Squash vine borer is a difficult to control pest of vine crops, particularly summer and winter squashes. Adults lay eggs for a three week period starting in late June. Cover lower section of stems with floating row cover or even aluminum foil to prevent egg laying. Look for and remove by hand any brown egg masses seen on the lower stems. Spraying carbaryl (Sevin) is more effective than using the dust formulation. If entrance holes and "sawdust" are seen, a wire can be inserted and threaded through the stem for some distance to kill developing larvae inside. Or slit stems lengthwise to find and destroy the caterpillar. Then bury slit stem section under some soil.


Garden flowers, whether annuals or perennials, benefit from "deadheading" after
flowering. By removing the spent flower heads, energy is used to produce more flowers or
foliage and roots.

In general, flowering requires lots of energy so it can be quite helpful to fertilize
flowering herbaceous plants once flowering begins. Fertilize once again before the end of the season.

Trees and shrubs should not be fertilized again until leaves begin to color and
drop this fall. Fertilizing, like pruning, stimulates new growth.


If you will be watering your lawn all summer to prevent dormancy, fertilize lightly now.
 

Second Week

Watch for cabbage worm, corn borers, cutworms, potato leafhoppers, potato beetles, aphids, tarnished plantbugs, and thrips on many vegetable crops. Obtain a copy of UW-Extension publication A2088 to help you manage insects in the home vegetable garden. Go to learningstore.uwex.edu.

Keep cole crops and potatoes covered with floating row cover to exclude cabbage
worm and leafhoppers. Cole crops such as cauliflower, broccoli, and cabbage can be sprayed or dusted with Dipel (Bacillus thuringiensis), a biological control product. M-trak is a similar biological control for potato beetles.


Seeds can continue to be sown throughout July for late crops of beets, bush beans,
carrots, chard, Chinese cabbage, cucumbers, kohlrabi, and corn. For summer planting, make the furrows and then moisten before sowing seeds. Cover with pre-moistened potting soil mix which will not be so likely to crust and crack.

Transplants of broccoli, cabbage, cauliflower, Chinese cabbage, collards, kale,
kohlrabi, onion sets, and onion plants can be planted for fall crops. “Harden-off” plants before planting, plant early in the day, and shade with floating row cover fabric to prevent sunburn of tender young plants.

Keep tomato plants well mulched and evenly moist to reduce the incidence of blossom end rot and cracking.


Oak, elm, ash, and maples infected with one of the wilt diseases will begin to show typical symptoms as the summer heats up. Bring samples of branches that have
recently wilted to your county UW-Extension office.
         

Begin looking for webs of fall webworm on woody plants. Control by cutting out
branches wrapped in webbing where possible. Spraying with the botanical insecticide B.t.
(Dipel, Thuricide, and others) is very effective on very young larvae.
 

Third Week

Fertilize asparagus plantings with 10-10-10 fertilizer now.

Summer raspberries should be coming in well now. Watch plantings closely for the
many possible insect and disease problems. Harvest fruit often and thoroughly to reduce the number of picnic bugs, yellow jackets and multi-colored asian ladybeetles competing with you for fruit. Viruses cause plants to be stunted and discolored, and fruits to crumble easily. See UW-Extension publication A1610 for pest descriptions and controls.

Ornamental kale, grown for its colorful foliage should be transplanted in mid-July.
When planted earlier, this cole family member tends to bolt causing misshapen, cone-shaped plants.

Watch for yellowing and wilted leaves on cole crops such as broccoli, cauliflower,
and cabbage. This may indicate black rot or club root, two serious diseases of these
crops.

Divide iris plantings every 3 - 5 years to renovate plantings and clean-out borer
infested plants.
    
 

Fourth Week

 Alpine currant shrubs infected with the anthracnose fungus will lose leaves and
sometimes completely defoliate by mid-summer. Fallen leaves will be spotted with the
fungus and should be diligently removed and destroyed to reduce the infection next year.

Honeysuckles susceptible to the common leaffolding aphid should be sprayed every 10 - 14 days with insecticidal soap. Pruning out infected stems every fall will reduce the population considerably but the prevalence of the insect means that others will probably fly in again. Since many species of honeysuckle are invasive especially in our natural areas, it might be best to consider replacing them with something else.