- Author: Belinda Messenger-Sikes
Nutsedges are aggressive and persistent weeds that commonly infest lawns, vegetable and flower gardens, and landscapes. These perennial sedges are a problem in lawns because they grow faster than turfgrasses and result in non-uniform turf. In landscape beds, nutsedge can grow up through mulches–even plastic mulches!
Yellow nutsedge grows throughout California while purple nutsedge can be found mostly in the south of the state and the Central Valley. Once established, nutsedge is difficult to control because it forms tubers in the soil that can live up to three years. The best approach is to prevent the weed's spread.
To help you identify and better manage this troublesome weed, UC IPM has updated the Pest Notes: Nutsedge. This fact sheet was revised by UCCE San Diego Area Integrated Pest Management Advisor Emeritus, Cheryl Wilen. Updates include additional nonchemical control methods and herbicides that are effective for early nutsedge infestations.
- Author: Cheryl A. Wilen
Nurseries and garden centers often sell a wide range of plants for use in gardens and landscapes. As a consumer, you may manage a complex array of different landscape plantings, including woody trees and shrubs, woody ground cover beds, annual flower beds, herbaceous perennial beds, and mixed plantings. This complexity often makes weed management difficult. An integrated approach is the most economical and efficient way to control weeds, so knowing strategies for managing weeds in a variety of landscapes can help.
Woody Trees and Shrub Beds
Control perennial weeds before planting, although weed control can also be done after planting. Densely planted areas will reduce weeds. Geotextile (landscape) fabrics rather than black plastic used with a shallow layer of mulch will keep weeds from emerging. If you mulch without a geotextile base, the mulch layer must be thicker to prevent weed emergence.
If needed, you can use a preemergence herbicide to control annual weeds and supplement with hand weeding and spot applications of postemergence herbicides for weeds that are not well-controlled by hand weeding, such as perennial grasses.
Woody Ground Cover Beds
Mature, woody ground cover beds should exclude most weeds; however, when ground cover is just establishing, weed growth is likely. Perennial weeds must be controlled before planting, although perennial grasses may be selectively controlled after planting with a grass-selective herbicide like sethoxydim (Grass-Getter). Annual weeds may be controlled with mulch plus a preemergence herbicide but rooting of stolons in new plantings may be affected. You will need to supplement with some hand weeding.
Annual Flower Beds
A dense planting in annual flower beds will help shade out and compete with many weeds. Flower species should be carefully selected for weed management compatibility. Periodic cultivation at 3- to 4-week intervals and between flower beds plant rotations will also suppress weeds. Perennial weeds must be controlled before planting. Annual weeds can be controlled with mulches, preemergence herbicides, frequent cultivation, and/or hand weeding. Control perennial grasses with grass-selective herbicides like clethodim, sethoxydim, or fluazifop. Avoid nonselective herbicides in annual flower beds after planting.
Herbaceous Perennial Beds
Weed management options in herbaceous perennial beds are similar to those for annual flowers, except that it is more important to eradicate perennial weeds as there will be no opportunity to cultivate or renovate the bed for several years; and fewer species are included on herbicide labels. Geotextiles may be used in these types of plantings. Manage weeds with mulches and supplement with hand weeding. If needed, use preemergence herbicides after hand weeding.
Mixed Plantings of Woody and Herbaceous Plants
Weed management in mixed plantings is complex because of the diversity of species. Different areas of the bed could receive different weed treatments. Site preparation is critical because post-plant herbicide choices are few. Plant the woody species first and control perennial weeds in the first two growing seasons, then introduce the herbaceous species. Plant close together to shade the soil. Group plants within the bed that will receive similar weed management programs.
In most landscape situations, herbicides should not normally be needed by home gardeners. Mulching, removal by hand, and proper irrigation (pattern and amount of water) are sufficient in most cases. Find more information in the UC IPM Pest Notes: Weed Management in Landscapes.
[Originally published as "Managing Weeds in Landscapes" published in the Fall 2018 issue of the Retail Nursery and Garden Center IPM News.]
/h2>/h2>/h2>/h2>/h2>- Author: Cheryl A. Wilen
- Posted by: Elaine Lander
Applying the wrong amount of pesticide can result in poor control if not enough is used; too much being applied can lead to waste and possibly illegal usage. If pest control is insufficient, the end result might be a second application that will be more expensive due to the cost of labor involved. If the pesticide is overused, the cost of the extra material is one consideration, but there might also be plant damage and a higher risk of pesticide moving off-site in runoff or leaching into groundwater.
In addition to reading the label carefully and making sure that pesticides are not washed off into storm drains, the applicator must be sure equipment is properly calibrated so that the proper amount of pesticide is applied. Poor calibration also can result in a lot of leftover pesticide in the sprayer. The less that is leftover, the less there is that must be disposed.
For liquid applications, one needs to know the area to be sprayed, how much pesticide product is needed to treat the area, and how much water to use so the solution will cover the treatment area. Because people walk at different speeds or otherwise may operate spray equipment differently, it is important that each individual applicator perform calibration steps, especially if the equipment is shared. Similarly, individual pieces of equipment may vary in performance, so it's important to calibrate each piece of equipment with the applicator, even if you have several of the same make and model.
Liquid applications are usually made using backpack sprayers (Figure 1) or hand cans with single nozzles and hand-operated pumps, vehicle-mounted tanks with gun-type nozzles and electric or gas pumps, or agricultural equipment with tank and boom supporting multiple nozzles.
Here we provide several methods you can use to calibrate equipment for specific broadcast spray situations. Follow the steps below to calibrate small sprayers for small treatment areas. Another method that can be used for larger sprayers and larger treatment areas is illustrated in Table 1. For estimating how much pesticide may be needed when spraying trees and shrubs, see the Ask the Expert! section on page 6 of the Green Bulletin.
Backpack & Hand Can Sprayers
- Measure out a representative area of 1,000 square feet (20 by 50 feet works well, or 5 by 200 feet is good if you are going to be spraying medians).
- Put clean water into the tank without any pesticide product.
- Walking at your normal pace and using your normal method of spraying, record the time it takes for you to spray the area you measured. It is best to do this two or three times to calculate an average time.
- Get a bucket or other container that has markings in ounces and spray water into it for the same amount of time required for you to spray 1,000 square feet. This amount is how much water you need to put in the tank for 1,000 square feet.
- Where will you be spraying? Measure the area to be treated. If you plan to make several small applications to a number of locations, you can combine the measured areas.
- How much pesticide product do you need? Many pesticide labels provide application rates as ounces per 1,000 square feet. If you have 2,000 square feet and the label says 5 ounces per 1,000 square feet, then you need 10 ounces of the pesticide product. If you have 500 square feet and the label says 5 ounces per 1,000 square feet, then you need 2.5 ounces.
- How much water do you need? In a previous step (above), you determined how much water is needed for you to cover 1,000 square feet. If you need to spray 2,000 square feet, you will need two times more water (2,000 divided by 1,000 equals 2); if you need to spray 500 square feet, you would need half as much water (500 divided by 1,000 equals 0.5).
Want to make your backpack sprayer calibration more accurate? Use the retrofit in Table 2 on page 7 of the Green Bulletin (provided by Danny Hirchag, Urban Forest Superintendent at UC Irvine) to improve calibration and ensure you are evenly applying the correct amount of pesticide product.
Let's Try an Example
- Output: You find it takes 130 seconds for you to treat 1,000 square feet with a specific sprayer. When you spray water with this sprayer into a bucket for that same amount of time, you find that you applied 22 ounces.
- Area: You need to treat three locations; one is 600 square feet, one is 900 square feet, and the third is 200 square feet. So you will be spraying a total of 1,700 square feet (600 plus 900 plus 200).
- Pesticide: The pesticide product label calls for a rate of 2 ounces per 1,000 square feet. Since you need to treat 1,700 square feet, you will need 1.7 times more pesticide (1,700 square feet divided by 1,000 square feet = 1.7). Multiply 1.7 by 2 ounces, and the result is 3.4 ounces.
- Consider pesticide product formulations: In this example, treatment of 1,000 square feet used 22 ounces of water but you are going to spray 1,700 square feet. Take 1,700 and divide it by 1,000, and the result is 1.7, so you need to add 1.7 times more water. For 1,700 square feet, we multiply 1.7 by 22 ounces of water, resulting in 37 ounces of water needed.
- If the pesticide product is a liquid formulation, then you will need to subtract the amount of liquid pesticide product added from the total amount of water needed. Therefore, to get 37 ounces of solution, you will need to subtract the 3.4 ounces of pesticide product added to determine the amount of water you must add (37 ounces total solution minus 3.4 ounces of pesticide equals 33.6 ounces of water).
- If the product is a dry formulation like a wettable powder, you will mix 37 ounces water and 3.4 ounces of dry pesticide product.
- In both cases, you would use the final solution to spray 1,700 square feet.
[Originally published in the Winter 2019 issue of the Green Bulletin, a newsletter that focuses on specific practices and information that landscape and structural pest management professionals. Subscribe to receive the newsletter electronically.]
/span>/h2>/h2>- Author: Cheryl A. Wilen
[Originally published as "Managing Weeds in Landscapes" published in the Fall 2018 issue of the Retail Nursery and Garden Center IPM News.]
Nurseries and garden centers often sell a wide range of plants for use in gardens and landscapes. As a consumer, you may manage a complex array of different landscape plantings, including woody trees and shrubs, woody ground cover beds, annual flower beds, herbaceous perennial beds, and mixed plantings. This complexity often makes weed management difficult. An integrated approach is the most economical and efficient way to control weeds, so knowing strategies for managing weeds in a variety of landscapes can help.
Woody Trees and Shrub Beds
Control perennial weeds before planting, although weed control can also be done after planting. Densely planted areas will reduce weeds. Geotextile (landscape) fabrics rather than black plastic used with a shallow layer of mulch will keep weeds from emerging. If you mulch without a geotextile base, the mulch layer must be thicker to prevent weed emergence.
If needed, you can use a preemergence herbicide to control annual weeds and supplement with hand weeding and spot applications of postemergence herbicides for weeds that are not well-controlled by hand weeding, such as perennial grasses.
Woody Ground Cover Beds
Mature, woody ground cover beds should exclude most weeds; however, when ground cover is just establishing, weed growth is likely. Perennial weeds must be controlled before planting, although perennial grasses may be selectively controlled after planting with a grass-selective herbicide like sethoxydim (Grass-Getter). Annual weeds may be controlled with mulch plus a preemergence herbicide but rooting of stolons in new plantings may be affected. You will need to supplement with some hand weeding.
Annual Flower Beds
A dense planting in annual flower beds will help shade out and compete with many weeds. Flower species should be carefully selected for weed management compatibility. Periodic cultivation at 3- to 4-week intervals and between flower beds plant rotations will also suppress weeds. Perennial weeds must be controlled before planting. Annual weeds can be controlled with mulches, preemergence herbicides, frequent cultivation, and/or hand weeding. Control perennial grasses with grass-selective herbicides like clethodim, sethoxydim, or fluazifop. Avoid nonselective herbicides in annual flower beds after planting.
Herbaceous Perennial Beds
Weed management options in herbaceous perennial beds are similar to those for annual flowers, except that it is more important to eradicate perennial weeds as there will be no opportunity to cultivate or renovate the bed for several years; and fewer species are included on herbicide labels. Geotextiles may be used in these types of plantings. Manage weeds with mulches and supplement with hand weeding. If needed, use preemergence herbicides after hand weeding.
Mixed Plantings of Woody and Herbaceous Plants
Weed management in mixed plantings is complex because of the diversity of species. Different areas of the bed could receive different weed treatments. Site preparation is critical because post-plant herbicide choices are few. Plant the woody species first and control perennial weeds in the first two growing seasons, then introduce the herbaceous species. Plant close together to shade the soil. Group plants within the bed that will receive similar weed management programs.
In most landscape situations, herbicides should not normally be needed by home gardeners. Mulching, removal by hand, and proper irrigation (pattern and amount of water) are sufficient in most cases. Find more information in the newly revised Pest Notes: Weed Management in Landscapes.
/h2>/h2>/h2>/h2>/h2>/span>
- Author: Karey Windbiel-Rojas
Controlling weeds can be challenging, but UC IPM provides many resources to help home gardeners and landscape professionals.
The newly revised publication Pest Notes: Weed Management in Landscapes by Area IPM Advisor Cheryl Wilen, presents an integrated approach to weed management to help ensure weed control efforts are effective, environmentally-sound and economical. This science-based publication includes information on methods such as pre-planting considerations, the importance of weed identification, nonchemical practices such as using mulches and barriers, weed management recommendations in different types of landscape plantings, and updated herbicide options.
See this updated publication and UC IPM's other 170 Pest Notes at http://ipm.ucanr.edu/PMG/PESTNOTES/index.html.
Also check out UC IPM's Weed Photo Gallery for help with identifying weeds in various growth stages.
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