Hort Update for Oct 20, 2014

Hort Update for Oct 20, 2014

Natural Needle Drop in White Pine
Natural Needle Drop in White Pine
In This Issue:
Major Symptom:
1. Broadleaf weed control still effective Continue spot treating with herbicides as needed
2. Too late to sow turfgrass Seed temporary cover crop to protect bare soil over winter
3. Laying sod Sod can be laid as long as it can be cut from sod fields
4. Dormant seeding Wait at least one month before dormant seeding
5. Changes in late fall fertilization Apply no later than first week of November; only up to .75 lb.
6. Weed control in warm season turf Glyphosate (RoundUp™ ) can be applied over dormant turf in about a month
7. Mow leaves into turf  Mow mulching leaves works as long as leaf layer not too thick
8. Fall tree pruning timing Wait until after leaf drop to prune trees and shrubs
9. Fall tree planting Late for evergreens, fine for deciduous trees
10. Natural needle drop or disease?  Positively identify the cause of needle browning
11. Late fall watering Might be needed if October remains dry; monitor soil
12. Mulching and cutting back roses Mulch, prune if needed, after plants are dormant; best to prune in spring
13. Still time to move perennials and roses?  Fall planting best done in September, special care needed for later plantings
14. Vegetable garden soil amendment Safe application of manure or compost in fall
15. Are any vegetables poisonous after a frost?  Do not harvest rhubarb after hard freeze
16. Potato storage Harvest and curing methods for best quality and storage
17. Prepare to winterize strawberry beds Winter mulch improves flower survival, improving next season's harvest
18. Pruning brambles Maintenance pruning for best production and disease control
19. Millipedes 1-inch long, dark brown worm-like insect with numerous legs; harmless

1. Broadleaf weed control still effective

Research shows that herbicides applied during fall for perennial broadleaf weed control, even when applied after frost, are very effective. There is also less risk of injury to dormant landscape trees and ornamentals. Continue to spot treat perennial broadleaf weeds. For information on specific herbicides used in research, see link below.

How late is too late to control broadleaf weeds?, UNL Turf iNfo


2. Too late to sow turfgrass

The risk of winter injury to Turf-type tall fescue and Kentucky bluegrass seeded after September is too high. Seeding is no longer recommended. Lay sod or wait to dormant seed.  If needed, seed a temporary cover crop to protect bare soil over winter. Perennial ryegrass would be the first choice. Annual ryegrass and winter wheat may also be used.

Late Seeding and Winterkill Risk, UNL Turf iNfo


3. Laying sod

Sod can be laid as long as it can be cut from sod fields and the soil is not frozen. Sodding in early spring or early fall is preferred. Sodding in late fall or winter can be done as long as winter irrigation is available to minimize winter dessication on exposed sites. Sodbed preparation is the same as for seeding and essential for rooting success.

Establishing Lawns from Sod, UNL Turf iNfo


4. Dormant seeding

Wait at least one month before dormant seeding. Wait until after soil temperatures are about 40F. If dormant seeding is planned, now is the time to do soil preparation to improve seed to soil contact. This is essential for success. Aerification, power raking, tilling or some other form of cultivation is recommended. 

Improving Success of Dormant Seeding, UNL Turf iNfo


5. Changes in late fall fertilization

Fall fertilization is still considered the most important time to fertilize turfgrass, but recommendations have changed. Previous recommendations were to apply nitrogen during early to mid-September and then make a heavy application of nitrogen fertilization at the end of the growing season (early to mid-November). However, nitrogen fertilizer uptake efficiency declines later into the fall. Fertilizer that isn't taken up by the plant sits in the soil until the following spring or is leached out during winter. Avoid too late fall applications. September fertilization is best to maximize recovery from summer stress and prepare for winter. For the last application of the season, apply it no later than the first week of November. Only apply up to .75 lb. of a fast release nitrogen source.

Rethinking Fall Fertilization, UNL Turf iNfo


6. Weed control in warm season turf

Glyphosate (RoundUp™ ) can be applied over the top of dormant buffalograss to control cool-season grasses and broadleaf weeds while not affecting the dormant buffalograss. Late fall (Nov-Dec) is the best timing for this application. The key is there is no green in the leaves of buffalograss at the time of application. It is safest to treat late in the fall when the target cool-season weeds are still green.


7. Mow leaves into turf

Mowing leaves works as long as the leaf layer not too thick.  It can also beneficial for the turf and for the environment. Tree leaves should be pulverized enough that they filter down into the turfgrass. After mowing, green grass blades should still be visible.

Keep Mowing to Mulch Those Tree Leaves, University of Nebraska-Lincoln


8. Fall tree pruning timing

Wait until after leaf drop to prune deciduous trees and shrubs. This ensures the plant as completed the hardening off process for winter. While deciduous trees can be pruned almost any time during the year, late February to early April is considered the ideal time. Use correct pruning cuts, leaving the branch collar and branch bark ridge but not leaving a branch stub. Do not use wound dressings or tree paints on pruning wounds. 


9. Fall tree planting

Deciduous trees can be planted up until the soil freezes, but the earlier the better to allow for some root development. For evergreens, it is best to fall plant in September to allow for root development and water uptake. Because evergreens retain green needles all winter, they are more prone to winter drying; hence spring browning and death. If evergreens are planted later, be sure clients are aware of the risks; and that it will be critical for them to water evergreens up until the soil freezes; and during winter thaws. The soil should remain moist, but not saturated, so evergreens do not go into winter in a dry condition.

For late planted evergreens, consider the use of an antitranspirant. Timely applications of a product, such as Wilt-pruf, can be helpful. These products can reduce moisture loss from evergreen foliage. They coat needle surfaces with a lightweight glue-like substance, which serves to prevent water from leaving the foliage. In general, they last about 5-6 weeks before the sun and wind render them ineffective. Applications should be made about 6 weeks apart, beginning around Thanksgiving, to protect valuable trees throughout winter. Antidessicants should be applied when air temperatures are above freezing so the liquid will dry on the leaf surface before it freezes, allowing for a better residual. One word of caution - be sure to clean out your sprayer after making an anti-desiccant application. This is a glue-like substance and will harden in the linings and clog sprayers. A simple soap and water solution flush will prevent damage to sprayer equipment.


10. Natural needle drop or disease?

Needle browning at this time of year may simply be natural needle drop, but it may also be due to a fungal disease. Positively identify the cause of needle browning before attempting control or removing a tree.

Most conifers naturally drop inner needles once every 3 to 5 years during September and October. It appears as all inner needles, from the top to the bottom of the tree, suddenly yellowing and browning. When touched, the needles easily fall off the branch. Current year and up to 2 to 3 year old needles on branch ends remain green and healthy.

Two blights that could cause some browning now in pines are Dothistroma and Diplodia. Close inspection of needles will help determine the cause. With Dothistroma needle blight, browning will be near the bottom half of the tree. Green needles will have reddish spots and bands on the needles. Brown needles will have turned brown from the tip down to a reddish lesion. With Diplodia tip blight, brown needles on the tips of branches will be stunted and brown. Fully grown brown needles may hang straight down as if wilted. Pine cones will have black fungal specks on their bases. Fungicides can be applied for both of these blights, but wait until spring when new growth is beginning to apply labeled fungicides or they will not be effective.


11. Late fall watering

While we have had adequate rainfall this growing season, monitor the soil moisture of evergreens and newly planted trees. In the absence of late fall rain, watering may be needed to ensure the soil remains moist up until it freezes. This will help avoid a repeat of last years' drying injury to numerous trees and shrubs. Adequate fall moisture is the most important factor to reducing the risk of winter injury from dessication.


12. Mulching and cutting back roses

Pruning is not needed during fall for shrub roses, such as Knock Out, Buck roses, or Nearly Wild.  They are very winter hardy and do not need special protection.  Prune in April, removing dead or damaged branches, and adjusting plant height. However, hybrid tea, grandiflora, floribunda and some cultivars of miniature roses need winter protection.  These plants may need pruning to allow them to fit beneath a winter protection method, such as a rose cone, and to remove very tall laterals that may be damaged by winter winds. The majority of pruning should be done in April as new growth begins.

Most roses are protected by covering them. The key is to wait until the plant is hardened off and temperatures are cold. Do not put rose protection in place until soil has frozen or night temperatures are consistently dropping into the 20s at night. One good mulching method is the encircle the rose with a chicken wire cage staked to hold it in place, then fill the cage with coarse leaves. For best growth, wait until April and then prune to remove winter killed wood. Or mound 8 inches of soil around the base of roses after soil temperatures have cooled in late fall to protect the plant crown. Use a well-drained soil for this rather than one high in clay. After mounding, moisten the soil mound. After the soil is frozen, apply coarse mulch.


13. Still time to move perennials & roses?

Fall planting of trees, shrub and landscape ornamentals is best done in September.  This allows the longest period for root development before winter conditions arrive.  Planting in late October and November greatly limits a plant's potential for root development, making it much more susceptible to winter injury. Keep plants well watered until the soil freezes.  Apply a 4-6" layer of coarse winter mulch in late November to mid-December help prevent frost heaving and hold soil moisture.  Water plants during warm winter periods when the soil is not frozen.


14. Vegetable garden soil

Vegetable garden soil amendment, by incorporating compost or manure, is a good way to improve garden soils. The addition of organic matter improves drainage in clay soils and the water holding capacity of sandy soils. It adds essential nutrients and increases beneficial microorganisms. However from a safety standpoint, manure must be handled and applied correctly. Only apply manures that have been aged for at least six months to minimize the risk of burning plants with excess ammonia. It is best to use manures that have been properly composted (to a temperature of at least 140 F.) to kill harmful E. coli bacteria that may be present in raw manure. Proper composting is critical for using manure in food gardens to avoid potential human illness. Manures from carnivorous animals should never be used. Additionally, if soils have high levels of salts, feed lot manure should be avoided as they will add to the problem.

Compost from lawn and garden plant materials carry a much lower risk of food pathogen.  But avoid using plants heavily infected with disease in your compost pile; disease pathogens may survive the composting process and infect plants the following year.

Using Manure and Compost as Nutrient Sources for Fruit and Vegetable Gardens, University of Minnesota Extension
Soil Amendments, Colorado State University


15. Are any vegetables poisonous after a frost?

This is a common question from home gardeners in fall. The only vegetable of concern is rhubarb, which should not be harvested or eaten when leaves are wilted and limp after a hard frost. Oxalic acid in the plant's leaves may move from the leaves into the leafstalk, making them toxic.  All rhubarb leaf stalks that have been exposed to freezing temperatures should be removed and discarded. 

The texture and storage potential of other vegetables are affected by freezing temperatures, such as lettuce, peppers, summer squash and sweet potatoes.  Some vegetables actually improve in flavor following freezing temperatures, including parsnip, Jerusalem artichoke and horseradish.


16. Potato harvest and storage

Potatoes grown for winter use should be harvested about two weeks after the vines have died; usually in mid-summer.  Complete harvest in fall before frost for best quality.  Freezing temperatures will reduce potato quality and storage potential, but does not make them poisonous. To check maturity, dig up one or two hills of potatoes. If the skins on the tubers are thin and rub off easily, the crop is not fully mature and will not store well. Wait a few more days before harvesting. The skins on mature potatoes remain firmly attached to the tubers. When harvesting potatoes, avoid bruising, skinning, or cutting the tubers. Brush away as much soil as possible, but for best storage do not wash them. Damaged potatoes should be used as soon as possible.

Before placing the potatoes in storage, the tubers should be cured. Cure potatoes at a temperature of 45 to 60 degrees Fahrenheit and high relative humidity (85 to 95 percent) for two weeks. Healing of minor cuts and bruises and thickening of the skin occurs during the curing process. Once cured, sort through the potatoes and discard any soft, shriveled, or blemished tubers. These potatoes may spoil in storage and destroy much of the crop. Potatoes should be stored at a temperature of 40 to 45 degrees Fahrenheit and relative humidity of 90 percent. Store in a dark location as potatoes turn green when exposed to light. If storage temperatures are above 45 degrees Fahrenheit, the potatoes will start to sprout after two or three months. When stored below 40 degrees Fahrenheit, potatoes develop a sugary, sweet taste. Sugary potatoes may be restored to their natural flavor by placing them at room temperature for a few days. Do not allow potatoes to freeze. Most modern homes have few good storage places for vegetables. A cool garage or basement may be the best site. Another possibility would be a second refrigerator.

Vegetable Harvest and Storage, University of Missouri Extension
Options for Storing Potatoes at Home, University of Idaho Extension


17. Prepare to winterize strawberry beds

Strawberry plantings must be mulched for winter protection to produce consistently in Nebraska. Mulching prevents or reduces winter damage to the strawberry crown and flower buds. Most unprotected strawberry cultivars are injured at 15°F. Plant vigor, moisture conservation, weed control and improved fruit quality are benefits from mulching that continues through the summer.

Apply loose mulch to a depth of four inches in late November or early December after the soil has frozen to a depth of 1/2 inch, or the temperature has dropped to the 20s. Do not apply the mulch too early in the fall as it can delay hardening off, making plants more susceptible to winter injury, and increasing crown rot. Suitable mulches include wood chips, pine straw, newspapers, coarse sawdust, straw, clean hay or any loose mulch that will not compact heavily. The mulch should remain on the strawberry plants until new growth begins, about mid-April. Blooming can be delayed by allowing the mulch layer to stay on the plants, but waiting too long for removal will reduce yield.

Row covers are an effective alternative to mulch. Unlike straw mulches, light penetrates the row cover material, increasing the number of blossoms formed by the strawberry plants, and consequently, the overall yield. One disadvantage to floating row covers is that they accelerate flower development. Be prepared to protect blossoms from late frost.

As early spring flowers begin to bloom, remove the row covers or mulch to allow for pollination, but recover the plants at night when frost is predicted. Be sure to remove only enough mulch to expose the leaves. Place this excess mulch in the walkways between the plant rows. Partial removal of the mulch allows for plant development but delays blooming by keeping the soil cooler and slowing plant growth.

Prepare Strawberry Plants for Winter, Iowa State University
Strawberries, Backyard Farmer on YouTube


18. Pruning brambles

After harvest, remove all of this year's fruiting canes (floricanes) by pruning them out as close to the crown as possible. It is best to remove these canes during the dormant season before new growth begins in spring. Also remove any canes showing symptoms of raspberry anthracnose, which causes slightly raised spots with gray centers and purplish margins on raspberry canes. These eventually girdle and kill canes. Infection can occur throughout the season during wet periods. Sanitation, through removal of infected canes, during the dormant season will reduce the potential for disease next year.

Raspberries, University of Missouri Extension
Anthracnose of Raspberry and Blackberry, Ohio State University
Pruning Raspberries, Backyard Farmer on YouTube


19. Millipedes

Millipedes are often described as wireworms by homeowners. These one inch long, dark brown, skinny critters with numerous short legs are not worms, but a type of mollusks, They accidentally enter buildings and basements and are often found crawling on the siding of homes. Millipedes are not harmful to plants, people, pets or buildings and control is not needed or recommended. Reducing mulch layers close to building foundations and managing soil moisture can help reduce millipede numbers.

Managing Millipedes and Centipedes, University of Nebraska-Lincoln in Lancaster County