Posts Tagged ‘no-till’

Burndown No-Till Fields

Friday, March 30th, 2012

Mark VanGessel, Extension Weed Specialist; mjv@udel.edu

Fields that will be planted to no-till corn or soybeans may have excess weed growth due to the warm winter. This will make burndown treatments more challenging, and in some cases it is unrealistic to expect complete control with only one application. In those cases, you may need an application now, followed by an additional application at planting. For weeds that are hard to kill with glyphosate, additional herbicides such as 2,4-D can enhanced the control (for instance, mustards); while other herbicide combinations can reduce glyphosate control (for instance, atrazine in combination with glyphosate for ryegrass control). Be sure to assess each field, and determine the best approach. Do not assume you can spray a week ahead of planting and achieve a clean seedbed to plant into.

Cover Crops, Winter Annual Weeds and Spring Vegetables

Friday, September 23rd, 2011

Mark VanGessel, Extension Weed Specialist; mjv@udel.edu

Using cover crops prior to early-spring vegetables like peas and sweet corn is becoming more common. One issue for growers who want to no-till into that killed cover is managing winter annual weeds, like henbit and chickweed. In this situation, glyphosate is usually used to kill the cover crops (such as barley, wheat, rye). But glyphosate often will not provide the necessary control of henbit or chickweed because the weeds have not started actively growing that time of year. One way around this is using a herbicide in the fall to “clean up the cover crop”. Using a broadleaf herbicide such as Harmony Extra or 2,4-D in the fall will control many of the broadleaf weeds and not limit crop rotation in the spring (replant intervals are 1.5 to 3 months). Then, when burning down the cover crop in the spring, the concern is killing the cover crop, and not worrying about the winter annual broadleaves that can be tough to control that time of year.

No-Till and Strip-Till Fresh Market Vegetables

Friday, April 22nd, 2011

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

Most fresh market vegetable crops are either grown under conventional tillage or plasticulture systems requiring significant tillage. From a soil health perspective organic matter is the driver for healthy soils and the more the soil is worked, the faster that organic matter is decomposed and lost from soils.

One solution for this dilemma is using no-till, where organic matter can be conserved or increased. The best success story with no-till vegetables has been with pumpkins, which are commonly direct seeded through a killed cover crop mulch (often hairy vetch or rye) or through crop residue (most commonly barley or wheat small grain stubble). The mulch provided keeps pumpkins off of the ground and has greatly reduced fruit diseases and improved quality. Other seeded crops such as sweet corn and snap beans have been successfully no-tilled in the region.

No-till also has been shown to work with transplanted crops. Systems were developed and tested for tomatoes on hairy vetch and for numerous crops transplanted through small grain cover from peppers to cantaloupes. There were several no-till transplanters developed and we tested one at UD back in the 1990s.

Incorporating leguminous cover crops into these systems can reduce nitrogen needs for the vegetable crop being grown. In the pumpkin no-till into hairy vetch system, typically no additional N will be needed.

There are several reasons why no-till has not been more widely adopted for vegetable crops. No-till vegetables cannot be grown for early crops which are often the most profitable, due to soil temperatures remaining cooler, longer. Establishment can be an issue, especially through thick cover crop mulches. Weeds are controlled partially by the mulches and herbicides can be used for residual control; however, weed escapes can be problematic because cultivation is not available as a tool. Certain pests such as slugs, mites, and several insects can be an issue in no-till. Drip irrigation is also more difficult to use in no-till.

An alternative that combines some of the benefits of no-till with conventional tillage is strip-till, where cover is maintained between rows and a 6-12 ft tilled strip is where vegetables are seeded or transplanted. Strips can be formed with narrow rotary cultivators or with strip till coulters. This allows for earlier crops and for better establishment. A subsoiler can be run in the strips to improve root development. Management of the strip area needs to be planned ahead of time so that cover crops do not get too large – strips are formed when cover crops are small. There is also potential to install drip irrigation in the strips. In a strip-till system weed management is critical and residual herbicides will be critical.

Research has shown that for many vegetables, yields in strip till and no-till are comparable or higher than similar season conventional or plasticulture production.

The following are some of the keys to success with no-till fresh market vegetables:

1) Well drained soils are best for no-till and strip-till.

2) Fields to be no-tilled or strip-tilled should have minimal weed seed banks and little or no perennial weed problems.

3) An effective cover crop is required for no-till and strip-till systems to work. The cover crop should produce enough biomass to cover the soil and provide mulch that limits light and weed germination. Winter cover crops that have worked well for vegetable no-till in our area are hairy vetch, crimson clover, rye, vetch-rye combination, ryegrass, and subterrenean clover. For late summer no-till vegetable crops, several of the millets have provided good cover.

4) The cover crop should be easy to kill by chemical or mechanical means and have little or no-regrowth potential. Proper timing of cover crop kill is necessary to avoid reseeding in no-till systems. For strip-till systems, strips need to be formed early in the growth stage of the cover.

5) Attention needs to be paid at planting in no-till systems to provide good soil-seed contact for direct seeding or root placement and firming for transplants.

6) Provision should be made for moving residual herbicides into the soil through the mulch cover. This may require overhead irrigation.

7) Provision should be made to manage weed escapes. This may require spot spraying or hand weeding.

 

Fields Not Treated Yet for No-Till Soybeans

Thursday, May 6th, 2010

Mark VanGessel, Extension Weed Specialist; mjv@udel.edu

Due to the warm weather and good growing conditions, weeds in no-till soybean fields are larger than “normal” for early May. A few things to consider if the fields have not been treated yet:

● Coverage is important due to dense vegetation, keeping gallons per acre in the 20 gallons per acre range is important.

● While 2,4-D can help with some highly sensitive species (primrose), replanting intervals and proximity to sensitive crops will limit its use now.

● Don’t try cutting rates, weeds are large and often reduced rates will not effectively control them, even higher rates may not provide 100% control.

● Choose your herbicides carefully; if multiple species are present more than one herbicide will be needed and be sure they are compatible with one another, and they are going to provide benefit to your situation

● Be realistic in your expectations, controlling large dense populations of weeds is difficult, prioritize those species that are of the biggest concern. Remember a follow up in-crop application may need to be needed sooner than usual after planting to help control some species not killed by burndown treatments.

Italian Ryegrass Control for No-Till Corn

Thursday, March 25th, 2010

Mark VanGessel, Extension Weed Specialist; mjv@udel.edu

Italian ryegrass is the same as annual ryegrass. The weed we struggle to control in wheat and barley is the same plant that is sometimes used as a cover crop. The same characteristics that make it a good cover crop are the same attributes that make it a pesky weed. Furthermore, it is the same species that has developed resistance to glyphosate and a number of other common herbicides.

Whether it was planted as a cover crop or there are scattered plants throughout the field, annual ryegrass can be troublesome to control in no-till corn. A trial for annual ryegrass control was conducted in 2009 at UD’s Research and Education Center. Treatments included glyphosate or Gramoxone Inteon and they were either applied alone, with atrazine, with Bicep II Magnum, with Resolve, or with Bicep II Magnum plus Resolve. Glyphosate control was about 85% control, but when tankmixed with atrazine or Bicep, control was reduced to 70 to 75% control. The addition of 1 oz of Resolve to glyphosate plus atrazine or glyphosate plus Bicep II Magnum increased annual ryegrass control to over 90%. The three-way mix of Gramoxone Inteon, Bicep II Magnum, and Resolve also provided over 90% control, and this was higher than any other combination with Gramoxone Inteon. Annual ryegrass (or Italian ryegrass) is difficult to control. The addition of Resolve improved ryegrass control. In our trial, corn planting was delayed at least 2 weeks after herbicide application and no injury from Resolve was observed.

Annual ryegrass should be sprayed early, 4 to 6 inches tall. Larger plants are more difficult to control and increase the likelihood of needing two herbicide applications to kill it.

Preplant Weed Control in No-Till Small Grains

Friday, September 18th, 2009

Mark VanGessel, Extension Weed Specialist; mjv@udel.edu

No-till small grains require a weed-free seedbed for best results. A weed-free seedbed results in warmer soils and less early competition for light and nutrients. Non-selective herbicides labeled for this use are glyphosate (various formulations) or Gramoxone Inteon. Apply a non-selective (or “burndown”) herbicide at least 7 to 10 days prior to planting. This is especially important when planting into fields where grassy weeds or perennial weeds are problems. Glyphosate is the preferred product if the field has a history of grassy weeds (annual bluegrass, ryegrass, etc.) or if perennial weeds (horsenettle, yellow nutsedge, hemp dogbane, etc.) are presented.

Additional herbicides for use with Gramoxone Inteon or glyphosate include:

Dicamba (Banvel) can be applied at 2 to 4 oz/A with the burndown. There are no planting restrictions with this low rate of Banvel. Otherwise, the interval is 1.25 days per 1 ounce of product; this is 20 days for 1 pint.

Valor SX has a label for tankmixing with a non-selective herbicide to provide residual weed control. A minimum of 30 days must pass, and 1 inch of rain/irrigation must occur, between Valor application and planting winter wheat. Labeled rate is 1 to 2 oz/A.

2,4-D: most 2,4-D products are not labeled for use prior to planting small grains. So be sure to read the label of the specific 2,4-D product you plan to use.

Fields Not Treated Yet for No-Till Soybeans

Friday, June 19th, 2009

Mark VanGessel, Extension Weed Specialist; mjv@udel.edu

Due to the rains a number of fields that will be planted to soybeans have not been burned down or need to be retreated. A few things to consider if the fields have not been treated yet: 1.) coverage is important due to dense vegetation, keeping gallons per acre in the 20 gallons per acre range is important; 2.) while 2,4-D can help with some highly sensitive species (primrose), replanting intervals and proximity to sensitive crops will limit its use now; 3.) don’t try cutting rates, weeds are large and often reduced rates will not effectively control them, even higher rates may not provide 100% control; 4.) choose your herbicides carefully; if multiple species are present more than one herbicide will be needed and be sure they are compatible with one another, and that they are going to provide benefit to your situation; and 5.) be realistic in your expectations, controlling large dense populations of weeds is difficult, prioritize those species that are of the biggest concern and be sure to address them first and remember a follow up in-crop application may be needed sooner than usual after planting to help control some species not killed by burndown treatments.

Some fields have been treated and horseweed was not effectively controlled, but the fields have not been planted yet. First, a few scattered plants will not reduce final yield, so determine if a treatment is needed in the first place. The two options are Ignite 280 or a product with chlorimuron (Canopy, Canopy EX, or Synchrony). If the chlorimuron products have been used in this spring, a second application is not advisable due to both concerns with crop safety and reports of inconsistent horseweed control with these products. Ignite 280 at 29 to 36 oz/A or chlorimuron products at a rate providing 1.7 oz wt of Classic (Canopy 4 oz; Canopy EX, 1.8 oz; Envive at 4.1 oz; or Synchrony at 2 oz). We do not have much experience with side by side comparison of these options, but both should provide over 75% control.

Grape Hyacinth Control in No-Till Fields

Friday, April 24th, 2009

Mark VanGessel, Extension Weed Specialist; mjv@udel.edu

Grape hyacinth has been showing up in no-till fields in Sussex County. The biggest problem with grape hyacinth is in soybeans, because it interferes with soybean harvest. It emerges in the fall and can grow to 8 – 10 inches tall. If the infestation is severe, the waxy succulent leaves will interfere with the cutter bar. We do not have a lot of experience with grape hyacinth at this point, but it appears that glyphosate at 1.5 times the normal rate is the best treatment (1.12 lbs acid equivalent per acre). Last spring we compared glyphosate at normal and 1.5 X rates, and included paraquat; both tank mixed with Canopy EX. The treatment that provided the best grape hyacinth control in the fall was the higher rate of glyphosate. Glyphosate in the spring was slow to kill the grape hyacinth; but in the fall, the number of stems was significantly lower and the plants were smaller. As with all perennials, one year of an aggressive treatment will really help, but it requires more than one year to “clean up” the field.

Should You Leave Simazine Out With Later No-Till Corn Plantings?

Friday, April 24th, 2009

Mark VanGessel, Extension Weed Specialist; mjv@udel.edu

In the past, it was recommended to use simazine (Princep) when the cornfields were sprayed early. I have been asked whether it is worthwhile to include simazine as a component of no-till spray mixes for later planted corn. Princep will not control emerged grasses, but it will provide residual control. Be sure to include paraquat or glyphosate to control the grasses that have already emerged, then simazine will be there to control later emerging grasses. In fields with a history of crabgrass and fall panicum problems, it is a good idea to include simazine even with later plantings.

Weed Control for No-Till Soybeans

Friday, April 10th, 2009

Mark VanGessel, Extension Weed Specialist; mjv@udel.edu

It’s time to consider your options for no-till soybean burndown programs, and it is particularly important if you have glyphosate-resistant horseweed (marestail). Weed control for no-till soybeans has become more complicated as glyphosate-resistant horseweed has spread and species-shifts have occurred because of over-reliance on glyphosate for soybean weed control. A new fact sheet, “Approaches to Pre-Plant Weed Control in No-till Soybeans” is available at www.rec.udel.edu/weedscience/Fact%20Sheets_web/NT_soybeans_08_WF19.pdf. This fact sheet discusses the need for a combination of non-selective herbicide plus a plant growth regulator (2,4-D or dicamba) plus a residual herbicide for consistent weed control. In addition, the disadvantages of waiting until late spring to spray no-till herbicides are discussed.