Hort Update for the week of 4/15/2009
1. Monitor soil temperature- Even if air temperatures are warm, it is important to monitor soil temperatures. Soil temperature of 40 degrees Fahrenheit is needed for most plant roots to begin growth and normal function, and weed seeds require a specific minimum soil temperature that varies by species for seeds to germinate. Weed management, seeding, planting, transplanting and many plant care practices should begin after soil temperatures warm to at least the minimum if not the optimum temperature for that practice or plant. Soil temperatures for the entire state are now available on the Backyard Farmer web site, under the Weather and Temps link.
2. Pre-emergence Herbicides and Crabgrass- Crabgrass preventers are pre-emergence herbicides. They only work when seeds are beginning to germinate and thus absorbing lots of soil moisture. If that moisture contains pre-emergence herbicide, seedlings will die.
Crabgrass is a warm season annual grass. It grows from seed each year. A minimum soil temperature of 50 to 55 degrees is needed for crabgrass seed to begin germination with most crabgrass seed germinating at higher soil temperatures. Pre-emergence herbicides for control of crabgrass are best applied just prior to germination to provide the longest period of control.
In Nebraska, apply pre-emergence herbicides for crabgrass from late April into early May in eastern Nebraska and during the second week of May in western Nebraska. If applied much earlier, a second application may be needed in mid to late June. Maintaining a dense, healthy turf that competes with crabgrass and raising the mowing height to 3 inches will also reduce crabgrass.
Kentucky Bluegrass Lawn Calendar, http://www.ianrpubs.unl.edu/sendIt/g517.pdf
3. Moles- Moles burrow underground feeding on earthworms, grubs and other insects. Burrows made while moles are searching for food tend to wander in no apparent direction and appear on the soil surface as raised ridges. When making feeding tunnels near the surface, moles may burrow up to one foot per minute. Trapping, the use of baits such as Talpirid or Tomcat, and repellents made with castor oil are the recommended controls to try.
Moles and Their Control, http://www.ianrpubs.unl.edu/sendIt/g1538.pdf
4. Earthworms leave small castings (small, hard mounds) leading to rough lawn surfaces. While the mounds are a nuisance and create some walking/mowing difficulty, earthworms are beneficial by increasing air and water movement in soil and helping with thatch decomposition. There are no pesticides labeled for earthworm control. Although some pesticides and fertilizers are known to have an impact on earthworms, none can be recommended as controls. Core aerifying, power raking and verticutting will break down some of the castings and reduce bumpiness. Use of a heavy roller is not recommended due to creation of soil compaction.
Earthworms (Nightcrawlers) in Lawns, http://lancaster.unl.edu/hort/Articles/2004/nightcrawlers.shtml
5. Seeding/Overseeding Cool Season Turfgrasses
Kentucky Bluegrass - April 1 to April 30
Tall Fescue - April 15 to June 15
Use a blend of improved cultivars. Determine which cultivars are available for purchase in your area; then refer to the National Turfgrass Evaluation web site for information about the cultivars http://www.ntep.org/
Kentucky Bluegrass Lawn Calendar, http://www.ianrpubs.unl.edu/sendIt/g517.pdf
Tall Fescue Lawn Calendar, http://www.ianrpubs.unl.edu/sendIt/g558.html
6. Winter injury on evergreens appears as a fairly uniform browning, often on the south or west facing side of a tree and on outer plant parts. Evergreens lose moisture on sunny winter days. If the soil does not contain enough moisture to replace the loss, needles dry out and turn brown from the tip down. When soil is moist, roots may not be able to absorb it due to frozen soil or damaged roots. To reduce winter desiccation, provide adequate moisture to plants throughout the growing season. For now, wait to prune winter damaged areas until after new growth begins to better evaluate the extent of damage and to avoid pruning healthy buds the plant needs to repair damage.
7. Cold Temperature Injury to Budding Trees- When trees and shrubs begin to bud and leaf buds are killed or damaged by cold temperatures, a healthy plant will develop secondary buds and continue to leaf out. If flower buds are killed or damaged, the tree will not develop new flower buds for this season. They will develop flower buds for next year.
8. Vole Damage- An apple tree sample brought to the Douglas County Extension office showed voles gnawed off roots and gnawed the bark two feet high on the trunk. When gnawing encircles a tree trunk, the tree is girdled and dies. Protect trees from vole damage during winter with cylinders of hardware cloth placed around trunks in the fall. Vole populations in an area might be reduced by not using landscape fabrics and avoiding mulch layers deeper than two to three inches.
Controlling Vole Damage, http://www.ianrpubs.unl.edu/sendIt/g887.pdf
9. Tree selection for Nebraska- Due to pine wilt disease and the potential for emerald ash borer to enter our state in future years, Scotch pine and green and white ash trees are no longer recommended for planting in Nebraska at this time. Planting a variety of trees for diversity in tree species is important. When selecting trees to plant, avoid Scotch pine, green and white ash, and possibly trees that appear to be over-planted in your area.
For a list of trees for Nebraska, visit the Nebraska Forest Service web site or click on "Trees for All of Nebraska" or "ReTree Nebraska".
10. Planting Vegetable Gardens- A vegetable garden cannot be planted in one day. Cool season vegetables are planted in early spring, usually after the soil warms some and becomes dry enough to work. Warm season vegetables need to be planted after the danger of frost, sometime in May. Read the seed packet or transplant tag for general planting information.
Planting and Harvesting Times for Vegetable, http://www.extension.iastate.edu/Publications/PM534.pdf
11. Season Extenders may include hot caps, black plastic, cold frames, low tunnels and cultural practices. They are used to extend the harvest season of a plant beyond what is typical for the crop. They may be used to warm soil for earlier spring planting or to protect plants from frost in spring or fall. Season extenders are enjoyable for home gardeners to use and can be economically beneficial for market gardeners. Season extenders must be used correctly to extend the harvest season of a crop.
Information sources include:
Early Season Extension Using Hotcaps, http://www.ianrpubs.unl.edu/sendIt/g1745.pdf
Introduction to Season Extension, http://www.extension.org/article/18366
12. Red Clover Mites are small mites are often found on west and south facing windows and walls in spring. These mites overwintered under siding and window frames. When temperatures warm, clover mites become active. A wet washcloth or paper towel will control the pests on windows and walls. These nuisance mites do no damage to people, pets, or the house structure. Insecticides are not recommended for use indoors. An outdoor perimeter spray applied in the fall will help keep the mites from entering the home to overwinter.
Clover Mites, http://lancaster.unl.edu/pest/resources/CloverMites312.shtml
| Current Problems: | Major Symptom: |
| Lawns | |
| 1. Soil temperature | Knowing soil temperature important for plant care practices |
| 2. Pre-emergence herbicides | Timing of application important for weed control |
| 3. Moles | Raised tunnels created by moles burrowing for food |
| 4. Earthworms | Hard soil mounds create rough surface for lawn |
| 5. Seeding/overseeding | Seed cool season turfgrasses in April |
| Trees & Shrubs | |
| 6. Winter injury on evergreens | Needle browning; often on south or west side of tree |
| 7. Cold temperature injury to budding trees | Secondary buds on healthy trees will replace damaged buds |
| 8. Vole damage | Gnawing on bark and roots |
| 9. Tree selection | Select the right tree for the site and function |
| Gardens | |
| 10. Planting vegetable gardens | Planting time determined by vegetable type |
| 11. Season extenders | Extend a plants production beyond what is typical for the crop |
| Household Pests | |
| 12. Clover mites | Numerous red mites on sunny sides of homes indoors & outdoors |
1. Monitor soil temperature- Even if air temperatures are warm, it is important to monitor soil temperatures. Soil temperature of 40 degrees Fahrenheit is needed for most plant roots to begin growth and normal function, and weed seeds require a specific minimum soil temperature that varies by species for seeds to germinate. Weed management, seeding, planting, transplanting and many plant care practices should begin after soil temperatures warm to at least the minimum if not the optimum temperature for that practice or plant. Soil temperatures for the entire state are now available on the Backyard Farmer web site, under the Weather and Temps link.
2. Pre-emergence Herbicides and Crabgrass- Crabgrass preventers are pre-emergence herbicides. They only work when seeds are beginning to germinate and thus absorbing lots of soil moisture. If that moisture contains pre-emergence herbicide, seedlings will die.
Crabgrass is a warm season annual grass. It grows from seed each year. A minimum soil temperature of 50 to 55 degrees is needed for crabgrass seed to begin germination with most crabgrass seed germinating at higher soil temperatures. Pre-emergence herbicides for control of crabgrass are best applied just prior to germination to provide the longest period of control.
In Nebraska, apply pre-emergence herbicides for crabgrass from late April into early May in eastern Nebraska and during the second week of May in western Nebraska. If applied much earlier, a second application may be needed in mid to late June. Maintaining a dense, healthy turf that competes with crabgrass and raising the mowing height to 3 inches will also reduce crabgrass.
Kentucky Bluegrass Lawn Calendar, http://www.ianrpubs.unl.edu/sendIt/g517.pdf
3. Moles- Moles burrow underground feeding on earthworms, grubs and other insects. Burrows made while moles are searching for food tend to wander in no apparent direction and appear on the soil surface as raised ridges. When making feeding tunnels near the surface, moles may burrow up to one foot per minute. Trapping, the use of baits such as Talpirid or Tomcat, and repellents made with castor oil are the recommended controls to try.
Moles and Their Control, http://www.ianrpubs.unl.edu/sendIt/g1538.pdf
4. Earthworms leave small castings (small, hard mounds) leading to rough lawn surfaces. While the mounds are a nuisance and create some walking/mowing difficulty, earthworms are beneficial by increasing air and water movement in soil and helping with thatch decomposition. There are no pesticides labeled for earthworm control. Although some pesticides and fertilizers are known to have an impact on earthworms, none can be recommended as controls. Core aerifying, power raking and verticutting will break down some of the castings and reduce bumpiness. Use of a heavy roller is not recommended due to creation of soil compaction.
Earthworms (Nightcrawlers) in Lawns, http://lancaster.unl.edu/hort/Articles/2004/nightcrawlers.shtml
5. Seeding/Overseeding Cool Season Turfgrasses
Kentucky Bluegrass - April 1 to April 30
Tall Fescue - April 15 to June 15
Use a blend of improved cultivars. Determine which cultivars are available for purchase in your area; then refer to the National Turfgrass Evaluation web site for information about the cultivars http://www.ntep.org/
Kentucky Bluegrass Lawn Calendar, http://www.ianrpubs.unl.edu/sendIt/g517.pdf
Tall Fescue Lawn Calendar, http://www.ianrpubs.unl.edu/sendIt/g558.html
6. Winter injury on evergreens appears as a fairly uniform browning, often on the south or west facing side of a tree and on outer plant parts. Evergreens lose moisture on sunny winter days. If the soil does not contain enough moisture to replace the loss, needles dry out and turn brown from the tip down. When soil is moist, roots may not be able to absorb it due to frozen soil or damaged roots. To reduce winter desiccation, provide adequate moisture to plants throughout the growing season. For now, wait to prune winter damaged areas until after new growth begins to better evaluate the extent of damage and to avoid pruning healthy buds the plant needs to repair damage.
7. Cold Temperature Injury to Budding Trees- When trees and shrubs begin to bud and leaf buds are killed or damaged by cold temperatures, a healthy plant will develop secondary buds and continue to leaf out. If flower buds are killed or damaged, the tree will not develop new flower buds for this season. They will develop flower buds for next year.
8. Vole Damage- An apple tree sample brought to the Douglas County Extension office showed voles gnawed off roots and gnawed the bark two feet high on the trunk. When gnawing encircles a tree trunk, the tree is girdled and dies. Protect trees from vole damage during winter with cylinders of hardware cloth placed around trunks in the fall. Vole populations in an area might be reduced by not using landscape fabrics and avoiding mulch layers deeper than two to three inches.
Controlling Vole Damage, http://www.ianrpubs.unl.edu/sendIt/g887.pdf
9. Tree selection for Nebraska- Due to pine wilt disease and the potential for emerald ash borer to enter our state in future years, Scotch pine and green and white ash trees are no longer recommended for planting in Nebraska at this time. Planting a variety of trees for diversity in tree species is important. When selecting trees to plant, avoid Scotch pine, green and white ash, and possibly trees that appear to be over-planted in your area.
For a list of trees for Nebraska, visit the Nebraska Forest Service web site or click on "Trees for All of Nebraska" or "ReTree Nebraska".
10. Planting Vegetable Gardens- A vegetable garden cannot be planted in one day. Cool season vegetables are planted in early spring, usually after the soil warms some and becomes dry enough to work. Warm season vegetables need to be planted after the danger of frost, sometime in May. Read the seed packet or transplant tag for general planting information.
Planting and Harvesting Times for Vegetable, http://www.extension.iastate.edu/Publications/PM534.pdf
11. Season Extenders may include hot caps, black plastic, cold frames, low tunnels and cultural practices. They are used to extend the harvest season of a plant beyond what is typical for the crop. They may be used to warm soil for earlier spring planting or to protect plants from frost in spring or fall. Season extenders are enjoyable for home gardeners to use and can be economically beneficial for market gardeners. Season extenders must be used correctly to extend the harvest season of a crop.
Information sources include:
Early Season Extension Using Hotcaps, http://www.ianrpubs.unl.edu/sendIt/g1745.pdf
Introduction to Season Extension, http://www.extension.org/article/18366
12. Red Clover Mites are small mites are often found on west and south facing windows and walls in spring. These mites overwintered under siding and window frames. When temperatures warm, clover mites become active. A wet washcloth or paper towel will control the pests on windows and walls. These nuisance mites do no damage to people, pets, or the house structure. Insecticides are not recommended for use indoors. An outdoor perimeter spray applied in the fall will help keep the mites from entering the home to overwinter.
Clover Mites, http://lancaster.unl.edu/pest/resources/CloverMites312.shtml
