Kelly Feehan kfeehan2@unl.edu
In last week’s column I talked about knowing when to do nothing for landscape pests.
The “doing nothing” approach was in reference to applying pesticides at this time of year. Since most of us want to “do something” to maintain landscapes, here is a fall “to-do” list.
When it comes to pests, sanitation is important. Fall sanitation is the removal and disposal of dead or dying plant material from gardens to reduce overwintering pathogens and insects. Some diseases and insects overwinter on weeds, so don’t overlook cleaning up weeds near gardens.
Plant debris can be tilled under or removed and destroyed or added to compost. If the material comes from a plant with a pest problem or a weed that has gone to seed, it is best not to compost this material unless the pile is well managed. For information on composting garden material, refer to NebGuide G810 Garden Compost at www.ianr
pubs.unl.edu/sendIt/g810.pdf
The tops of herbaceous perennials and ornamental grasses are often left over winter to add interest to the winter landscape. If such a plant had a disease or insect problem during the growing season, it is best to remove the tops during fall. Whenever possible, wait until after the first freeze to remove the tops of perennial flowers and grasses.
Continue to mow lawns to prevent turfgrass going into winter too tall and to break down or remove tree leaves. Lawns left too high for winter, or those covered with leaves, are candidates for damage from snow mold disease and voles.
It is acceptable to mow tree leaves and leave them on the lawn as long as there is not a noticeable layer of leaves on the surface after mowing.
Lawns do not need to be mowed any lower than they are during spring and summer. Just continue to mow as long as the grass is growing. To promote rooting and stress tolerance, it is recommended to maintain the same height all year. For Kentucky bluegrass, that is 2.5-3.5 inches tall, and for turf-type tall fescue, the recommended height is 3-3.5 inches tall.
If you prefer or need to lower the height of a lawn over winter, the height of Kentucky bluegrass can gradually be lowered to 1.5-1.75 inches tall, and turf-type tall fescue can be mowed as low as 2.5 inches tall. However, rooting and stress tolerance can be improved by maintaining a taller height year round and this can lead to less pest damage.
Check mulch layers in landscape beds. If permanent mulch is too deep or is mounded against plant stems, this greatly increases the risk of vole damage and crown or root rots. Permanent mulch layers, such as wood chips, should only be 2-4 inches deep and always kept 6 inches to 1 foot away from plant stems.
While most plants should not be fertilized from mid-August to mid-November, cool season turfgrass, like Kentucky bluegrass and tall fescue, should be fertilized. The last lawn fertilization of the season is best timed with the last mowing, usually late October or early November.
Late fall fertilization provides many benefits for lawns. One benefit is to avoid fertilizing too early in spring when the soil is cold. Lawn fertilization in early spring increases the chance of disease and insect lawn problems.
The key when using late fall fertilizations is to not turn around and fertilize again in late March or early April. Wait until late April or early May.
Contact Kelly Feehan, Extension educator, at 563-4901 or
email her at kfeehan2@unl.edu
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