Deer tend to damage young smooth-barked trees
It is time to protect the trunks of smooth-barked trees like young maples from deer rubs if deer live in the neighborhood.
Deer rub their antlers on trees and often use the trunks of smooth-barked trees. This can damage the bark and even kill trees if the damage goes all around the trunk.
Wrap the trunks with tree wrap, chicken wire or plastic snow fencing to a height of 5 feet to help protect the tree. This protection can be removed in early spring.
• Fertilize your lawn in early September to improve the color and vigor of the grass. Nitrogen is the most necessary nutrient required, although too much nitrogen can cause excessive top growth and disease problems. A rate of 1 pound of nitrogen per 1,000 square feet of lawn is adequate for most lawns.
Many soils in the Chicago area have adequate levels of phosphorus, so your lawn probably does not need it. Some villages ban the use of phosphorus to improve water quality because it can fuel algae growth in creeks, streams, ponds and lakes.
If you only fertilize your lawn once a year, this is the best time to do it.
• Autumn also is a good time to core aerate your lawn to reduce soil compaction and thatch if you did not aerate in spring. Core aerating once a year is enough for most residential lawns with normal use.
Very high-use lawns benefit from being aerated twice a year. It also provides an opportunity for overseeding to help improve and thicken the lawn. Core aerating is best done when the ground is somewhat moist.
Keep new grass seed moist for good germination, and leave the soil/grass plugs on the lawn to break up and filter back down to the soil level. The plugs typically break down in seven to 14 days.
Mark sprinkler heads and light fixtures in the lawn so they will not be damaged.
• Divide perennials that bloomed in spring and summer as needed. It is best to do this work early in the month so the plants have time to establish before winter sets in. Mulch the newly planted divisions.
• Pythium blight is showing up in some lawns. Look for small, round to irregularly shaped, sunken patches of matted grass that are generally 1 to 2 inches wide and up to 6 to 12 inches wide that quickly appear during hot or cool, very wet, calm weather. Initially, the grass leaves appear water-soaked and dark during the early morning.
Diseased areas quickly fade from reddish brown to light brown as the grass dies and then becomes matted. A fluffy, white to purplish gray, cobwebby mold may cover blighted grass when the air is saturated with moisture. Pythium can be easily spread by water running off the lawn, mowing while the grass is wet or by foot traffic.
There are some cultural practices you can implement to help combat pythium. Aerate the lawn to help reduce soil compaction, improve drainage and reduce thatch. Avoid mowing the lawn when it is wet and increase the mowing height. Consider doing some grading if there are low areas in the lawn that tend to hold water. Avoid frequent light sprinkling of the lawn if you are irrigating, and water early in the day so that the lawn dries out before the evening. It is best to water less frequently and deeper.
If the disease is causing lots of damage, preventive applications of fungicides can be made when the weather is hot (above 80 degrees), humid and rainy with night temperatures at or above 68 degrees.
• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.