November 5, 2013 in Agronomic Crops
Mark VanGessel, Extension Weed Specialist; firstname.lastname@example.org
Delaware Department of Agriculture and MANA (Makhteshim Agan of North America) have approved a state label (24c) for use of Glory herbicide for winter wheat and barley. The active ingredient is metribuzin, formulated as a 75% DF. GLORY herbicide was requested for control of ALS-resistant chickweed. Glory is the only formulation of metribuzin with this special label in DE. In addition to chickweed, UD Weed Science has also had encouraging results with control of corn speedwell, jagged chickweed, henbit, and knawel when applied to weeds 3 inches or less.
Application timing is from 2 leaf stage of the small grain until jointing; and rate is dependent on crop stage. Application timing and rate are given in the table below.
RECOMMENDED POSTEMERGENCE BROADCAST APPLICATIONS OF GLORY
GLORY may be tank mixed with Axial, Harmony, Harmony Extra, 2,4-D, MCPA, Banvel/Clarity, Osprey, or Powerflex herbicides. A nonionic surfactant containing at least 80% active ingredient may be used in GLORY tank mixes. Do not use a crop oil concentrate or methylated seed oil (MSO) or any adjuvant containing vegetable or petroleum oils as crop injury may result.
Precautions from the Glory label:
● Do not use on soils containing less than 0.75% organic matter.
● On irrigated cereals, do not apply more than 0.5 inch of water for the first irrigation. The maximum amount for each additional irrigation should not exceed 1 inch. Allow a minimum of 14 days between the first irrigation and subsequent irrigations.
Risk of crop injury can increase when applications are made:
1. when the crop is under stress such as winterkill, frost damage, disease, drought or excessive moisture, severe grazing, or when these conditions follow the application;
2. in combination with fluid fertilizer especially with the addition of surfactant;
3. prior to the growth stage specified on this label;
4. to soils high in lime or sodium, a pH greater than 7.7, calcareous, gravelly, thinly covered, or exposed subsoil areas;
5. to fields where cereal seeds have been planted less than 1 inch deep;
6. to a sensitive wheat or barley variety; and
7. to frozen soil or crop still in winter dormancy.
Crop rotations range from 4 to 18 months. Refer to the label for rotations
There are wheat and barley varieties that are sensitive to Glory and significant injury can occur (a number of varieties are listed on the label). However, the list of varieties on the label does not address the majority of varieties grown in Delaware. We have tested some varieties and at rates higher than the recommended amount, and we have seen significant leaf burn and stunting with a few varieties (listed under fair to poor below). The difficulty in obtaining this data for is the number of varieties and the increasing number of new varieties.
Based on our experiences, the following is a limited number of wheat and barley varieties we have used in various trials and our relative ranking for crop safety:
Good safety: Coker 9553, Oakes, Sunburst, Truman
Moderate to good crop safety: Chesapeake, FS 950 (barley), Nomini (barley), and Thoroughbred (barley)
Moderate crop safety: SS 520, FS 627, Shirley, USG 3251, USG 3555, USG 3770
Fair to poor crop safety: VA 05W 258, USG 3209, and SS 560
Based on my scale, those varieties rated moderate may show stunting if Glory is applied under situations prone to crop injury, but I would not expect to see yield loss.
The following are two articles (one from Univ. of Tennessee and the other from Mississippi State Univ. on this issue) addressing variety selection in more detail:
Evaluation of Wheat Varieties for Metribuzin Tolerance (Mississippi State Univ):
Sencor Tolerance for Selected Wheat Varieties (Univ. of Tennessee):
In summary: Glory is a good option for ALS-resistant chickweed and with experience we may find it helpful with other troublesome species. We know some varieties differ in their sensitivity to metribuzin, and most varieties have not been tested. So we recommend using Glory on fields with ALS-resistant chickweed and being cautious on varieties with no previous experience.
● Be sure to follow the label to reduce the risk of crop injury.
● Do not use on sandy soils with organic matter less than 0.75%; which includes sandy knolls in portions of some fields.
● We recommend use of metribuzin only in fields planted with a grain drill (not recommend on fields where seeds were broadcast and incorporated with vertical tillage tool or disc).
● Be sure to use the rate recommended for your crop stage.
● Do not double-crop vegetables after small grain harvest.