Green Industry Resources
Hort Update- Seasonal Information for the Green Industry
Hort Update for May 8, 2013
|1. Summer Patch||Symptoms appear in summer. Fungicide treatments in May.|
|2. Yellow Nutsedge||Apply herbicides prior to June 21st.|
|Established in 7 Nebraska counties. Important to monitor.|
|Trees & Shrubs|
|4. Spruce Mites||Mite active in April and May. Monitor for damage.|
|5. Common Scale Insects||Inspect lilac and euonymus for scale insects.|
|6. Efficient Tree Watering||Drip irrigation, soaker hoses, slow dripping pails good watering methods.|
|7. Pruning Spring Blooming Shrubs||Time to prune is within one month after flowering.|
|8. Perennials for Dry Locations||Replacing high water use plants helps conserve water, ensures plant survival.|
|9. Preventing Rabbit Damage||Protect new growth from rabbit nibbling, e.g. bulbs, Asiatic lilies, hosta|
|Fruits & Vegetables|
|10. Inspect for Early Infestation of Squash Bugs||Flat, brownish-black insects cause wilting and death of cucurbits|
|11. Grass Clippings and Herbicide||Check current label guidelines, and follow recommendations|
|12. Inspect for Cabbage Loopers||Holes in cabbage heads and leaves. Greenish, looping caterpillar|
1. Crabgrass control (Professional vs. Homeowner) - Crabgrass is a warm season annual that begins germination after soil temperatures are above 50°F. This occurs sometime in May in Nebraska. Late April to early May is the ideal time to apply preemergence herbicides for crabgrass when only one application is being made.
Professionals often need to apply products earlier; hence they use sequential applications with the first application typically made in March to late April and the second application made early to mid-June. For sequential applications, the highest label rate can be divided in two and then two equal applications made. If a single application is still used, apply no later than the first week of May (assuming typical weather).
One application at the highest label rate will usually provide adequate control, but sequential applications improve control.
Application Timing of Premergence Herbicides University of Nebraska-Lincoln
2. Fertilization (Professional vs. Homeowner) - For people who do their own lawn care, the first fertilization of the season is best from early to mid-May; after soils warm and as the spring growth flush occurs. Heavy spring fertilization is best avoided. Cool-season grasses need little encouragement to grow and applying too much fertilizer in April causes excess shoot growth at the expense of root growth and uses up valuable storage products needed for summer performance. Applying a limited amount of N (up to 0.5-0.75 lbs. N/1000 ft2) in April will produce quick green-up while not significantly sacrificing long-term performance. Applying rates this low can be difficult for the average do-it-yourselfer (DIY) because of product and equipment availability, spreader accuracy, etc.
Most professionals have the equipment, products, and experience to apply at the lower rates needed when more applications are used. Professionals apply fertilizer earlier, and often make more applications (5 to 6 vs. 4 or less for do it yourselfers); but they do not apply more annual N than the typical do-it-yourselfer.
Most homeowner products are formulated to apply 1 lb. N per 1000 sq. ft. if applied at the label rates. Homeowners could adjust the spreader to make a ¾ to ½ rate application if applying earlier and more frequently.
When purchasing combination preemergence herbicide and fertilizer products in spring, purchase products as low in N as possible and/or with the most slow release N.
Early Spring Lawn Maintenance University of Nebraska-Lincoln
3. Slow Release Nitrogen (N) sources - These extend the window of N release and minimize the potential growth spike after application. This promotes healthy turfgrass less prone to stresses and disease. Slow release sources include sulfur- or polymer-coated urea, urea formaldehyde, methylenediurea, dimethylenetriurea, or natural organic nitrogen. These are listed on the label as “slowly water soluble” or “water insoluble”.
Fertilizer products with these N sources are becoming more readily available and very common in do-it-yourself products in retails stores. Pay attention to N sources followed by an asterisk and be sure read and follow the entire label of any product before purchasing and applying. Selecting fertilizer with slow release N should be made a high priority.
4. Spruce and drought - Drought injury or winter dessication is not unusual on Arborvitae, broadleaf evergreens like boxwood, and poorly sited Yew. The injury we are seeing on spruce is unusual and demonstrates our exceptional drought. Reports of spruce discoloration range from yellow to brown to mauve.
If discoloration is observed, check spruce for signs of life. Bend a branch to see if it is still pliable. Scrape the bark to check for green tissue beneath. Crumble a bud or two between two fingers to check if soft and still green. When signs of life are found, wait until after new growth begins before pruning. This allows time for new growth and some recovery. As a rule of thumb, do not give up on an evergreen branch or plant until about June 1.
5. Pruning cautions - We are past the ideal window to prune ornamental and shade trees. In April and May, bark is tender and easily torn. Increased sap flow will lead to “bleeding” which is unattractive but does not harm trees. With oak trees, sap can attract beetles that may transmit oak wilt. Pruning also removes stored food a tree may need to survive another year of drought or to recover from last year’s drought.
Avoid pruning in April and May. Even though pruning can resume in June and July, avoid excessive or unneeded pruning this year.
6. Pruning Evergreens - Delay pruning drought or winter injured evergreens until June 1. Most evergreens can be left to grow naturally. Pruning in not needed. If pruning is desired, spruce, Arborvitae and Japanese Yew are typically pruned just prior to spring growth. Pines are pruned after their new growth has elongated into the “candle” stage.
Pruning Evergreens Colorado State University
7. Diplodia Tip Blight Control - This fungal disease commonly infects older Austrian, Ponderosa and other pines causing new growth to be stunted, black pycnidia to develop on the bottoms of cones and entire branches to die with needles turning brown and hanging straight down as if wilted. This disease can be controlled with fungicides. The first application is made at budbreak (around the third week of April), a second just before needle emerge, and a third 7 to 14 days later. The active ingredients of Thiophanate-methyl, Propiconazole, Copper Salts of Fatty & Rosin Acids, or Bordeaux mixture are recommended fungicides.
Diplodia Tip Blight of Trees Nebraska Forest Service
8. Rose pruning - This should be done in mid to late April, as new growth begins to remove any winter injury. Pruning of hybrid tea roses can also be used to manipulate the size, timing and number of flowers that a plant produces in the coming summer months. Prune hybrid tea roses to a height of 12-24 inches. Completely remove dead, diseased, weak or broken branches by cutting them back to the crown. Also remove branches that cross or rub each other.
On shrub roses, after eliminating any winter injury, remove up to one third of the oldest, woodiest stems each year, cutting them back to the plant’s crown. This encourages the growth of new, vigorous stems from the plant crown and eliminates the development of many old, woody branches with poor flower production. It also increases air circulation through the plant, reducing potential for disease problems.
Rose Pruning University of Illinois Extension
rule, divide summer and fall blooming perennials during spring, beginning just before new growth begins. Many perennials benefit from division once every three to five years. Dividing is also a good way to propagate perennials. This year give special consideration to soil moisture and the possibility of dry summer conditions when deciding to divide.
Dividing Perennials University of Minnesota
10. Mulching perennials - during summer will help conserve soil moisture and keep weed growth to a minimum. Apply 2-4 inches of chipped or shredded bark, straw, grass clippings or other suitable material. Keep mulch away from plant stems and crowns as this can create an environment conducive to crown and root rots.
11. Dry summer considerations - When buying new plants this spring, keep in mind that dry conditions are forecast again this summer, followed by the potential of water restrictions. Even drought tolerant plants need supplemental watering during the establishment year, so base new plantings on your willingness to irrigate and water budget.
12. Horticultural oil applications - The season for dormant oil applications has passed. Application of lighter grade products, such as summer or horticultural oils can be made during the growing season, but do not make oil applications during bloom or as new growth is emerging. Oil can be used again, beginning with the first cover spray on apples & pears starting 10 days after petal fall, to control mites and immature scales as they hatch.
To prevent damage to foliage or fruits, never use a summer oil with captan, carbaryl, or other sulfur-containing pesticides. Allow at least 14 days between applications of sulfur-containing compounds and the use of a summer oil. Apply oil at temperatures above 40 degrees Fahrenheit and below 90 degrees Fahrenheit.
Fruits Spray Schedules for Homeowners University of Missouri Extension
13. Too late for fruit tree pruning - Fruit tree pruning is best done from late February through March, before trees begin to break bud. Avoid pruning during bloom, and as new growth emerges to avoid spreading fireblight and creating wounds that can be invaded by other diseases. Occasional summer and fall pruning may be needed, but keep it to a minimum.
14. Fruit irrigation - Consider installing drip irrigation to supplement the water needs of tree and small fruit plantings if dry conditions persist. Fruits require abundant water to ensure vigorous plant growth, and good fruit bud initiation for next season.
15. Vegetable crop rotation - Crop rotation between vegetable families can reduce insect and disease damage. Insect populations and disease-causing organisms tend to increase when their host is continuously grown in the same location. For crop rotation to be effective, you need to know the genetic relationship between common garden crops.
- Aster family- lettuce, endive, Jerusalem artichoke
- Bean family- pea; snap, cow, and fava bean
- Brassica family- cabbage, broccoli, broccoli rab, cauliflower, Brussel sprouts, collards, kale, turnip, rutabaga, kohlrabi, Chinese cabbage, radish
- Cucurbit family- cucumber, summer squash, winter squash, cantaloupe, watermelon
- Goosefoot family- beet, Swiss chard, spinach
- Grass family- corn
- Lily family- onion, garlic, leek, shallot, chive
- Parsley family- carrot, celery, celeriac, parsnip, fennel
- Solanaceous crops- tomato, eggplant, pepper, potato, ground cherry, tomatillo, garden huckleberry
Crop rotation is especially effective with soil home diseases. Rotation periods are three to five years, meaning that a crop should not be grown in the same plot during that time. Obviously, this is difficult in a small garden where pathogens are spread throughout the planting bed by tilling; however, container plantings can become part of the rotation for added space.
16. Eliminating weedy trees & shrubs - To remove weedy trees and shrubs, cut the plants down close to the ground and paint the freshly cut stumps with one of the mixtures below. If the stumps are not treated, they will resprout and grow back.
A number of herbicides are recommended for this. For the best results, apply them immediately after cutting to the freshly cut surface. Treatments include:
- 2,4-D Ester mixed with diesel
- 50 - 100% solution of Glyphosate
- Tordon RTU
Use caution when applying Tordon, due to its long residual in the soil and the high risk of injury to nearby trees. It is best avoided in landscape situations or wherever there are nearby trees.
2013 Guide to Weed Management University of Nebraska – Lincoln
- Establishing Lawns
- Turf iNfo Timely Tips
- Overseeding damaged areas
- Which turfgrass to plant?
- Wait on grub control
Fruits & Vegetables