|
 Turf rusts generally appear in cooler temperatures and we
recently experienced a period of cool days with low humidity and
very cool nights. The result was a nice crop of rust in the
lawn.
All turfgrasses can be infected with rust fungi, but Kentucky
bluegrass, perennial ryegrass, tall fescue, and zoysiagrass tend
to be most susceptible. Early symptoms of rust diseases include
light yellow flecks on leaves and stems, giving the lawn a
yellow cast. The leaf tissue ruptures at these yellow spots, and
spores of the fungus are produced. The pustules may be yellow,
orange, brown, or red. The spores rub off very easily on hands,
shoes, clothing, and animals. Often, the disease goes unnoticed
until you mow the lawn and see that your white shoes are covered
with a dusty coating of rust-colored spores.
Severely infected turf appears thin and tinted yellow, red, or
brown, depending on the fungus and time of year. The turf
becomes weakened, unsightly, and more susceptible to injury from
environmental stress and other disease pathogens. Grasses
growing slowly under stressful environmental conditions (such as
big swings in temperature and moisture) are most susceptible to
rust, particularly when water, fertility, and soil compaction
are inadequate for good growth. There are also varieties with
resistance and susceptibility to rust.
Management measures should target stress areas. Leaf wetness is
required for infection, so it is important to water early in the
day so the turf can dry before night. Water turf infrequently,
but to a depth of 6 inches or more at each watering. Avoid
frequent, light sprinklings. Fertilize to keep the grass growing
about 1 inch per week in summer and early fall droughts. Use
balanced fertilizer and do not apply excessive nitrogen. As the
grass grows, it pushes rust-infected leaves outward, making it
easy to mow and remove infected blades. It may be helpful to
catch these clippings and remove them from the area. Mow
regularly to remove infected leaf tips, but avoid mowing below
the recommended height for the particular turf species. Prune
surrounding trees and shrubs to improve light penetration and
air circulation around densely shaded areas.
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If the lawn is badly infected or the combination of rust and
other stress produces a poor lawn and forces a renovation, it is
ideally done in late August or early September. Use a blend of
turf cultivars with resistance to rust, but beware that what was
once resistant may no longer be. The rust fungi keep evolving
and eventually defeat the old-line resistance. Preventive
fungicides are available, but they offer only a temporary
solution. The fungicide treatments tend to be costly and time
consuming. Daconil is the most common fungicide used on turf,
but following the management practices will produce better
long-term results. To offer a ray of hope, diseases must have
ideal conditions to develop. Just wait for a major weather
change and the rust will go away. At least for a while.
Pruning
Several calls have come in about pruning trees and shrubs this
time of year. Simply put, major pruning is not recommended at
this time. Sure, you can lop off the odd branch about head high
to avoid injury while mowing. However, regular pruning is a
rejuvenating process for the plant. This means stored energy
meant for the winter will be used to produce new shoots. These
new shoots won’t be sufficiently aged to survive the winter.
Then you will have some dead tips to cut off at the proper time
anyway.
High sap flow trees such as maples and gums are best pruned in
December. The same goes for oaks to avoid oak wilt as a
secondary problem. Fruit trees and other deciduous trees are
best done in late February or early March. Flowering trees and
shrubs may be done as soon as they complete flowering.
Evergreens are best done in late June.
[By JOHN FULTON, COUNTY EXTENSION
DIRECTOR SERVING LOGAN, MENARD, AND SANGAMON COUNTIES] |
