Section 18 for sulfoxaflor (Transform WG) on sorghum for sugarcane aphid

The EPA has granted a Section 18 for the use of Transform WG (50% a.i. sulfoxaflor) on sorghum for managing sugarcane aphid in certain counties in Virginia. The expiration date is November 30, 2018. All applicable directions for use, restrictions, and precautions on the label, and Worker Protection Standards, must be followed except as modified in the Section 18 document. In part, the Section 18 lists a foliar application rate of 0.75-1.5 oz of product per acre, with a maximum of 2 applications per year, resulting in a seasonal maximum application rate of 3.0 oz of product per acre per year. Please be sure to read and follow the entire label and Section 18. Thanks to the Virginia Department of Agriculture and Consumer Services, Office of Pesticide Services, for their assistance.

Peanut-Cotton Infonet Update

The Peanut-Cotton Infonet is up and running for the 2018 growing season. As in previous years, the website will provide:

  • Maximum, minimum, and average air temperatures
  • Average soil temperature at a 4 inch depth
  • Daily and accumulated (from May 1) peanut heat units
  • Daily and accumulated (from May 1) cotton degree-days
  • Daily and total seasonal (from May 1) rainfall
  • Last effective spray date for peanut leaf spot
  • Sclerotinia blight risk
  • Frost advisory (from September 25th to completion of harvest)

The web address has changed slightly and the website can be found here.

Soil temperatures in southeastern Virginia have been cool over the past couple of weeks (average less than 60 °F), and cool, wet conditions in some fields will favor seedling diseases in early planted crops. A warming trend over the next week will hopefully result in more favorable planting conditions towards the beginning of May.

For questions or concerns regarding the Peanut-Cotton Infonet throughout the growing season, contact Dr. Hillary Mehl (hlmehl@vt.edu).

Wheat Disease Update – April 19, 2018

Currently the wheat crop in Virginia is near flag leaf emergence, and flowering will start within a couple of weeks. As flowering begins, be sure to monitor the FHB risk in your area using the Fusarium Head Blight Prediction Center website. Currently, most of Virginia has low risk for FHB infection. The exception is the Eastern Shore where risk is moderate to high in many areas, especially on susceptible varieties such as Shirley. Powdery mildew outbreaks have been observed in some fields this season, and incidence of common rust has been sporadic. Stripe rust has been found in North Carolina, but it has not been reported from Virginia. The 2018 Wheat Fungicide Efficacy Table can be downloaded below. Once wheat approaches the heading stage, keep in mind that strobilurin fungicides should no longer be applied. For specific wheat disease management recommendations or assistance with disease identification, contact Dr. Hillary L. Mehl (hlmehl@vt.edu).

2018 NCERA 184 Wheat Fungicide Table

Wheat Disease Update – April 12, 2018

Currently the wheat crop is in the jointing stages, and we are several weeks away from flowering. Currently the Fusarium head blight (FHB) risk is low for most areas of the state except for the Eastern Shore. These conditions may change as the wheat crop approaches flowering, so be sure to continue monitoring the FHB risk tool (http://www.wheatscab.psu.edu/). Moderate to severe outbreaks of powdery mildew have been reported from several fields in the past week. Be sure to scout wheat fields at this time and apply fungicide when disease is first detected. The updated Wheat Fungicide Efficacy Table can be downloaded below. For specific wheat disease management recommendations or assistance with disease identification, contact Dr. Hillary L. Mehl (hlmehl@vt.edu).

 

NCERA 184 Wheat fungicide table 2017_Final

Invitation to NRCS/VCE Cover Crop Training–April 12, 2018

You are invited to attend the 2018 Natural Resources Conservation Service/Virginia Cooperative Extension Cover Crop Training on Thursday, April 12, 2018 (9:00 am to 3:30 pm) at the Virginia Tech Tidewater Agricultural Research and Extension Center (6321 Holland Rd., Suffolk, VA). The event is free and open to the public. Lunch will be provided–please RSVP to Gail White (guwhite@vt.edu) by April 5 so that she can get a head count for lunch. Here is the agenda: Final Agenda_April 12 2018

If you are a person with a disability and desire any assistive devices, services or other accommodations to participate in this activity, please contact the Tidewater Agricultural Research and Extension Center at 757-657-6450 during business hours of 8 a.m. and 4:30 p.m. to discuss accommodations 5 days prior to the event.  *TDD number is (800) 828-1120.

Another Online Dicamba Training Option

Earlier this week I posted links to BASF’s online dicamba training module.  Here is another online training option from Monsanto.  Again, Michael and myself encourage applicators to attend face-to-face trainings, but know that extenuating circumstance exist.  You can access the training at the link below.

 

http://www.roundupreadyxtend.com/stewardship/education

 

As always, feel free to contact us with any questions or concerns.

Online Dicamba Training

BASF’s dicamba training module is now live! To access the training visit engeniastewardship.com and click on the training tab.

This online training module satisfies the US EPA requirement for mandatory dicamba training. It should be utilized as an alternative training opportunity for individuals who are unable to attend in-person trainings. BASF and Virginia Cooperative Extension strongly encourages in person training because it offers opportunities for dialogue and questions. Individuals can request in person trainings on engeniastewardship.com.

This online training module will NOT fulfill the Engenia® herbicide label requirement for training in the following states:

  • Alabama, Arkansas, Georgia, Indiana, Mississippi, Missouri, and North Carolina: state university / extension training only
  • Kentucky and Louisiana: in-person training only
  • Florida, Illinois, Iowa, Minnesota, North Dakota, Oklahoma: Currently in-person training only

Time to start planning for horseweed/marestail

Charlie Cahoon and Michael Flessner, Extension Weed Specialists at Virginia Tech

Horseweed or Marestail

Horseweed is a winter or summer annual and a member of the asteraceae family.  In the winter annual cycle, horseweed germinates in the fall and overwinters as a basal rosette. The following spring, the rosette bolts, reaching 1.5 to 6 feet in height.  While most populations of horseweed in the region emerge in the fall, significant spring emergence can occur under certain conditions.  Spring germinating horseweed does not form a rosette.  Leaves are alternate, simple, linear to oblanceolate in shape, and lack petioles.  Leaf margins are either entire or toothed.  Flowers consist of numerous small heads arranged in a panicle with many white ray flowers and 20 to 40 yellow disk flowers.  Seed are small and have a pappus of tan to white bristles (resemble dandelion seed).  Seed are easily dispersed by the wind, allowing it to quickly spread to nearby fields and within fields.

Bolted horseweed. Virginia Tech Weed ID Guide.

Herbicide resistance:  Regionally, glyphosate- and ALS-resistant horseweed are widespread.  If you are unsure of the resistance status in your fields, assume resistance to glyphosate and ALS herbicides. Resistance to Gramoxone (PS I-inhibitor) has been reported in Delaware.

Management:  Horseweed is more prevalent in no-till fields compared to fields prepared conventionally.  Tillage can be useful in the long-term management of horseweed.  Chemical control of horseweed is more consistent when the weed is in the seedling or rosette stage compared to bolting plants.  Traditionally, glyphosate and ALS-inhibiting herbicides effectively controlled horseweed, however, biotypes resistant to these herbicides are wide-spread.  Chemical control of glyphosate- and ALS-resistant horseweed requires a postemergence herbicide to control emerged horseweed and depending on application timing a residual herbicide for horseweed yet to emerge.  Due to the prolonged germination period, horseweed seedlings can emerge 5 to 6 weeks after residual herbicide application, thus fall applications of residual herbicides often have limited effectiveness for spring emergence.

Herbicides used for emerged plants include 2,4-D (1 pt in the fall or 1 qt in the spring), dicamba, Liberty, Sharpen, or Gramoxone plus a triazine herbicide (atrazine or metribuzin).   Preliminary research from Virginia and North Carolina suggest Elevore (a new auxin herbicide from Dow) also controls horseweed well.  Fourteen days are required between Elevore application and corn or soybean planting and 30 days prior to cotton planting.  Herbicides providing residual control include Valor SX, triazine herbicides (atrazine, simazine, and metribuzin), and ALS-inhibiting herbicides (if horseweed is not ALS-resistant).

Horseweed seedlings do not tolerate shade.  Thus a well-established cover crop, or dense crop canopy can be very effective to manage horseweed infested fields.

Horseweed rosette. Virginia Tech Weed ID Guide.

Soybeans: The key to managing horseweed in in soybeans is to control it prior to planting. Horseweed needs to be controlled prior to bolting (grow upright); this may require an application weeks prior to planting.  Glyphosate plus 2,4-D (1 qt/A), glyphosate plus dicamba or glyphosate plus Sharpen will effectively control glyphosate- and ALS-resistant horseweed when they are small.  Pay attention to rotational restrictions of preplant burndown herbicides when planning burndown applications and planting.  If horseweed are susceptible to the ALS-inhibiting herbicides, Classic-containing herbicides (i.e. Canopy, Valor XLT, Envive, Surveil) are effective.  If applications are made early pre-plant, herbicides containing Valor SX or metribuzin or the Authority products can be included to provide residual control, or a second application of a non-selective herbicide may be needed at planting. Liberty or Gramoxone also control small horseweed and can be used as a part of the burndown application.  If horseweed is present at planting, Gramoxone plus a residual product (Valor SX, Authority products, metribuzin, or Sharpen) is suggested in regions with later emerging horseweed.    Foliar applied PPO-inhibiting herbicides (Blazer, Reflex or Flextar, Resource, and Cobra) DO NOT control emerged horseweed.  For Liberty Link varieties, Liberty applied postemergence controls small horseweed.   Classic and FirstRate are postemergence options where horseweed are susceptible to the ALS-inhibiting herbicides and are small.

Cotton:  Like soybean, horseweed needs to be controlled prior to cotton planting.  Burndown combinations of glyphosate plus 2,4-D/dicamba plus Valor SX is normally in order.  Again, pay attention to plant-back restrictions when timing burndown applications.  Glyphosate plus Sharpen is also effective, but requires a long waiting period between application and cotton planting.

Corn:  In no-till corn, Gramoxone plus triazine, glyphosate plus atrazine plus 2,4-D or dicamba, and Liberty plus atrazine applied burndown of emerged seedlings and residual control of glyphosate- and ALS-resistant horseweed.   Consult labels for waiting interval prior to planting corn.  Atrazine alone will provide good residual control of horseweed.  Dicamba and 2,4-D are the most effective postemergence herbicides.  For small emerged horseweed, foliar applied HPPD-inhibitors or Liberty plus atrazine are effective.

Sorghum:  Glyphosate plus Sharpen or Gramoxone plus a triazine applied burndown.  Atrazine alone or in combination with Gramoxone applied preemergence for residual control and control of small emerged horseweed.  Atrazine can be used postemergence for control of small horseweed.  However, similar to corn, 2,4-D and dicamba are the most effective postemergence options.

Small grains:  2,4-D, dicamba, Quelex, or Huskie will provide effective postemergence control of horseweed in small grains.  Harmony Extra is also very effective on small horseweed that is susceptible to ALS-inhibiting herbicides.

Fall fallow application:  In fields with a history of horseweed, fall applied herbicides can be helpful in managing the weed.  However, a fall herbicide application will not substitute for a spring burndown application.  Target applications for emerged horseweed plants in the late fall after one to two killing frosts.  2,4-D or dicamba should serve as the base for these applications.  Glyphosate is often suggested in combination with 2,4-D and dicamba to control other winter annual weeds.

To see similar information on other problematic weeds consult the Virginia Pest Management Guide: Field Crops at http://pubs.ext.vt.edu/456/456-016/456-016.html or the Mid-Atlantic Field Crop Weed Management Guide at https://extension.psu.edu/mid-atlantic-field-crop-weed-management-guide.

As always, don’t hesitate to contact Michael or myself with any questions or concerns.