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Hort Update for Sept. 26, 2016

Lawns
Major Symptom:
1. Mowing Stay at same height; mow annual weed seedheads
2. Aeration

Important practice to relieve soil compaction; promote root growth

3. Late for seeding

Can still do in eastern Nebraska; risky in western Nebraska

4. Fall fertilization Apply now, use 50% fast release N, 50% slow release N
5. New lawn calendars

Available at http://turf.unl.edu/turf-advice

6. White grubs

Poor time of year to control; wait and control the new generation next year

7. Perennial weed control Best to wait to apply first applications after first light frost
   
Trees & Shrubs  
8. Leaf drop Some trees dropping leaves early; stress related or minor leaf disease
9. Planting time Fall is a good time to plant the right tree correctly
10. Natural needle drop Will begin soon on evergreens; most noticeable on white pine
   
Landscape Ornamentals  
11. Cutting back perennials Providing habitat for beneficial insects
12. Perennial division Fall is ideal time to divide and transplant
13. Digging tender plants

Dig and store for winter

14. Bulb fertilization Maintain bulb vigor with fall fertilization
   
Fruits & Vegetables  
15. Planting garlic Fall best time to plant for production of larger bulbs
16. Fruit cultivar ID Very difficult from fruit alone, some tools available
17. Bramble pruning Maintenance pruning for best production and disease control
18. Storing fruits & vegetables Harvest at proper time and store at correct temperature/humidity
19. Average fall freeze dates October 10 in eastern Neb.; September 20 in western Neb.
20. Protecting plants from freezing temperatures Guidelines for predicting fruit or vegetable damage
21. Garden clean up Helps control pests and diseases
22. Compost pile success Maintain moisture; avoid adding diseased plants
   
Miscellaneous  
23. Fall invaders Lady beetles, spiders, boxelder bugs, wood roaches & more
24. Backyard Farmer Open House Gardeners are invited to this year's final garden open house, Saturday October 1

1. Mowing - Continue to mow at the same height used during spring and summer. A height of 2.5 to 3.5 inches is best for cool season turfgrass. Return grass clippings to the turf. Mow often enough so as not to remove more than one-third of the total canopy height at one time. Mowing at the shorter end of the recommended range will require more frequent mowing than at the higher end of the range. Mowing too infrequently – called scalping- accelerates growth rate, reduces quality and canopy density, and encourages weed encroachment.

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2. Aerationshould not be overlooked. Core aeration, or plugging, is an important turf practice that is needed to relieve soil compaction and promote a vigorous root system along with infiltration of rain and irrigation water. Because of summer annual weed pressure in spring, lawn aeration is preferred in fall for cool season turfgrasses; and needed if soil compaction exists. Use the vertical type that pulls cores; preferably do not use a drum aerator. 

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3. Window for seeding closing- Fall is the most successful time for seeding cool season turfgrasses. However, the window has or is closing for seeding this fall. The ideal window for seeding tall fescue is August 15 to September 15 and about August 20 to September 20 for Kentucky bluegrass. While both can be seeded up until late September in eastern Nebraska, later seeding is riskier. The window for seeding has closed for western Nebraska.

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 4. Fall fertilization windows are late summer (late August into September) and early fall (late September through October). In late summer, apply 0.50 to 0.75 lbs. of nitrogen fertilizer per 1000 square feet to help turf recover from summer stress. Check nitrogen sources on label and select a produce that is 50% fast release nitrogen (N) and 50% slow release N. Young lawns (less than 10 years old) and lawns with poor density and quality can benefit from a mid-fall fertilizer application. For this, fertilizers should contain mostly water soluble (WSN) nitrogen sources.

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5. New UNL lawn calendars available at http://turf.unl.edu/turf-advice. Two new management calendars are available. One for cool-season lawns and one for warm-season lawns.

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6. White grub control ineffective now- Mid to late September and October are poor times to control white grubs. The larvae are full grown and more difficult to kill with insecticides; and they have or will very soon stop feeding and no additional damage will be sustained this season. For effective control of white grubs, and prevention of turf damage, wait until next season to control the next generation of grubs. This is permissible on lawns with a history of damage.

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7. Perennial broadleaf weed controlis most effective with spot treatments of herbicides applied during fall. It is best to wait until after the first light frost to begin making applications. When night temps begin to fall into the 30, plants initiate carbohydrate movement into the root system. This increases the movement of herbicide into roots to increase weed kill. Combination herbicides are generally more successful than individual active ingredients in controlling perennial broadleaf weeds.

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8. Early leaf drop can occur if trees sustained environmental stress or were infected by a minor leaf disease during summer. Otherwise healthy trees will be fine in the long run if infected by a minor leaf disease such as anthracnose or leaf blight. Most healthy trees are able to withstand one to two seasons of environmental stress as well; however, repeated years of stress can increase a trees susceptibility to other issues such as attack by borers. While nothing can be done about the weather, avoid other stresses such as over or under watering, over fertilizing with nitrogen, hitting trees with lawn mowers and not mulching or piling too much mulch over the roots and against the tree trunk. 

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9. Good time to plant trees - Fall is a good time to plant trees. Evergreens are best planted in September. Deciduous trees, those that drop their leaves, can be planted up until the soil freezes. A tree is a long term investment. Select a quality tree for the location and plant it correctly. Avoid the most common tree planting mistakes such as planting too deep, pruning or fertilizing with nitrogen at planting, not cutting girdling roots and amending the backfill soil.

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10. Natural needle drop will begin soon - Evergreens do not keep all of their needles forever. They retain one to three year old needles. Natural needle drop typically begins in September with interior needles suddenly and uniformly turning yellow from the top of the tree to the bottom. These yellow needles are easily knocked off of the tree by hand, wind or rainfall. Natural needled drop is just that. Natural and not of any concern. As a rule, pines hold their needles for two to three or more years and spruce trees hold needles five to seven years. Natural needle drop is most noticeable on white pines.

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11. Cutting back perennials – Insects, depending on their species, overwinter is a specific life stage – adult, egg, larva, nymph, pupa, etc. Many insects enter diapause, a stage of extended dormancy, to enable them to survive winter conditions. They seek out sheltered locations that provide some winter protection, such as hollow plant stems, leaf litter around the base of shrubs, tree bark flaps, or grass and perennial plant crowns. Or they may nest in the ground, in tree or shrub cavities or in wood. Plants with pithy or hollow stems like ornamental grasses, elderberry, raspberry, blackberry and sumac serve as good overwintering sites for solitary bees.

When working with clients on cutting back ornamental grasses and perennials in fall, landscape managers should recommend leaving 12-18” of stems in the garden to allow for increased beneficial insect overwintering habitat. Pollinators and butterflies will benefit from these additional amounts of winter cover.

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12. Dividing perennials is an important management practice for many species, helping to encourage vigorous growth and optimum blooming. Many perennials benefit from division once every 3-5 years. Dividing is also a good way to propagate perennials.

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13. Digging tender plant - tender bulb-like plants such as cannas, tuberous begonias, and gladioli are not hardy enough to survive Nebraska winters in the ground. Once frost has killed the top growth in fall, especially in cannas, cut off the foliage and dig up the rhizomes. Brush soil off the canna rhizomes and store them at 45 to 50 degrees F. Do not allow the rhizomes to freeze. Dahlia tubers must be dug each fall and stored in damp sawdust or peat at 60 degrees F. Divide the tuber clump in spring leaving a part of the true stem attached to the tuber. For more information on the correct temperature and humidity for storage, refer to the publication below.

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14. Bulb fertilization in fall is an important practice to maintain bulb vigor. Apply 5 tablespoons of 10-10-10 water soluble fertilizer or an equivalent amount of bulb fertilizer, plus two cups of bone meal per 10 square feet. 

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15. Planting garlic - Mid-September through mid-October is a good time to plant garlic for harvest next summer. Plant at least one month before the soil freezes. The bulbs will root and begin to sprout, then go dormant to continue growth next season. Garlic is started by planting small cloves, or divisions of the large bulb. The larger the clove, the larger the mature bulb will be at harvest. Do not divide the bulb into cloves until just before planting.

Garlic grows best in loose, loamy, fertile soil high in organic matter. Apply three pounds of 10-10-10 fertilizer per 100 square feet at planting time or use organic fertilizers such as blood meal. Plant the cloves 3 to 5 inches apart with points up and 1 to 2 inches deep. Allow 18 to 30 inches between rows or plant 5 inches apart in a wide bed row. Mulch fall planted garlic with 8 to 12 inches straw after the soil freezes.

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16. Fruit cultivar identification – In fall, a common question from gardeners with a favorite apple or pear tree is for identification of the cultivar from the color and shape of the fruit. This almost impossible to do, in fact, it’s really only realistic to give a general idea of possible cultivars.

One tool that may help in the identification is the New England Apple Association web site.

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17. 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.

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18. Storing fruits & vegetables is most successful if produce is harvested at the correct stage of maturity, cured or otherwise prepared properly for storage, and then stored at the temperature and relative humidity needed by each vegetable and fruit. For specifics on curing and best storage conditions for each fruit and vegetable, see:

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19.  Average fall freeze (32° F) dates are a measure of when the average first frost will occur in a region. They indicate that half of all autumn freezes will occur before the dates shown and half will occur after, based on 47 years of data from 1949-1995. In southeastern Nebraska that average autumn freeze date is approximately October 9 and September 21 in the northwest corner of Nebraska's panhandle. These dates are guidelines only. Freezing temperatures may occur before the dates listed below. Also remember that local microclimate conditions can significantly affect the occurrence of frost in your landscape.

These dates can be used as guidelines for gardeners growing late season vegetable crops. Frost sensitive plants will not tolerate freezing temperatures and must be taken inside before a freeze occurs or allowed to succumb to the end of the season.

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20. Protect fruits & vegetables from freeze damage - Average autumn freeze (32° F) dates are a measure of when the average first frost will occur in a region. They indicate that half of all autumn freezes will occur before the dates shown and half will occur after, based on 47 years of data from 1949-1995. In southeastern Nebraska that average autumn freeze date is approximately October 9 and September 21 in the northwest corner of Nebraska's panhandle. These dates are guidelines only. Freezing temperatures may occur before the dates listed below. Also remember that local microclimate conditions can significantly affect the occurrence of frost in your landscape.

These dates can be used as guidelines for gardeners growing late season vegetable crops. Frost sensitive vegetables will not tolerate freezing temperatures and must be protected to prevent damage. These temperature guidelines can serve as a guide when predicting potential flower bud damage to perennial fruit crops, such as fruit trees, brambles or strawberries.

Frost Resistance of Vegetables. From the Effects of Cold Weather on Horticultural Crops in Indiana, Purdue University.

  • Very hardy
    • Can withstand freezing temperatures and hard frost (less than 28° F) for short periods without injury.
    • Asparagus, collards, endive, kale, kohlrabi, lettuce, mustard, pea, potato, rhubarb, rutabaga, salsify, spinach, turnip
  • Frost tolerant
    • Can withstand light frosts (32-28° F) without injury.
    • Beet, broccoli, Brussels sprout, cabbage, carrot, cauliflower, celeriac, celery, chard, Chinese cabbage, Jerusalem artichoke, onion, parsnip, radish
  • Tender
    • Injury or killed by frost (32° F).
    • Snap bean, sweet corn, tomato
  • Warm loving
    • Cannot tolerate cold temperatures.
    • Lima bean, cucumber, eggplant, muskmelon, okra, pepper, pumpkin, summer squash, winter squash, sweet potato watermelon

Approximate Low Temperatures that Damage Dormant Plants and/or Flower Buds. From the Midwest Home Fruit Production Guide.

  • Apple, -30° F
  • Pear, -30° F
  • Peach and Nectarine, -15° F
  • Plum, -15° F
  • Cherry, -20° F
  • Apricot, -25° F
  • Strawberry, -10° F
  • Blueberry, -20° F
  • Blackberry (erect), -20° F
  • Blackberry (trailing thornless), -5° F
  • Raspberry (red), -30° F
  • Raspberry (black), -20° F
  • Grape, -15° F
  • Gooseberry, -30° F
  • Currant, -30° F

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21. Garden sanitation during fall involves cleaning up or tilling under plant debris in the vegetable garden and around fruit trees to reduce overwintering pests. The sooner this can be done after a plant dies or after fruit drops to the ground, the better. Plant pathogens are less likely to survive if organic matter is quickly decomposed. Remove plant debris or infected plant parts after each growing season.

  • Turn the soil after harvest to help break down small roots that may harbor nematodes, fungi or bacteria.
  • Gardeners may compost dead plants if they have a good composting system; otherwise, these piles may serve as a source of pathogens.
  • Prune or remove twigs and branches of woody plants affected with fire blight and other bacterial or fungal canker diseases.
  • Keep gardens weed free. Weeds often are another source of pathogens. Eradicate weeds to break the life cycle of pathogens and control them. Weed removal also can increase air movement and thus decrease conditions that favor disease development.
  • So that pathogens do not spread from one area to another, always disinfest machinery and other tools with steam, hot water under pressure, or a 10 percent solution of household bleach diluted with water.

Orchard sanitation is essential for good maintenance of fruit trees and small fruit plantings. Insects and diseases can overwinter on dead or infected plant material. Dried fruits or "mummies" carry disease organisms through the winter to attack next years' crop. Remove and destroy any fruits that have fallen to the ground, or those appearing to rot on the branches.

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22. Compost pile success begins with using the right combination of materials, called the carbon to nitrogen ratio (not too much green material and the right amount of brown material); chopping plant debris to increase surface area and speed decomposition; keeping the pile about as moist as a squeezed out sponge; and turning the pile frequently for aeration. It is also important to avoid adding pet feces since they may transmit disease. Meat, bones, grease, whole eggs, and dairy products should not be added because they attract rodents. Avoid adding diseased material and weed seeds to compost piles.

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23. Fall invaders are pests such as spiders, boxelder bugs, clover mites, wood roaches, and lady beetles that accidentally move indoors as they seek overwintering locations. Most are a nuisance. For crawling pests, a perimeter insecticide spray will help control them. For flying insects, use a silicone caulk to close openings.

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24. Backyard Farmer Open House, Saturday October 1 - Have your clientele ever asked about the Backyard Farmer Garden on UNL’s East Campus? Or would you like to see it and the completed Keim Hall courtyard landscaping project? See all of this and get your garden and turf questions answered on Saturday, Oct. 1, from 9:30 am to noon, at this year’s final Backyard Farmer Garden Open House.  

Nebraska Master Gardeners along with BYF host Kim Todd, associate professor and extension horticulture specialist, will be at the BYF garden to guide tours, talk about fall gardening, extended gardening and composting, as well as answer your gardening questions. There will be an opportunity to see Keim Courtyard and find out what went into the creation of this beautiful space.  

Bill Kreuser, assistant professor and extension turfgrass specialist; Cole Thompson, integrated turfgrass weed and disease management assistant professor; Keenan Amundsen, turfgrass genetics assistant professor; turf graduate students and the UNL Turf Club will be at the BYF Turf Garden on the north side of East Campus to answer your lawn questions. Tours will focus on lawn species demonstrations and the importance of selecting the right grass, turf weed identification and control strategies, mowing research and best lawn mowing practices and calibrating application equipment. The UNL Turf Club will hold lawn games with prizes.  

The BYF Garden is located at http://go.unl.edu/byfgarden and BYF Turf Garden is located at http://go.unl.edu/byf-turf-garden.   

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