In my last issue of the Maryland Weed Reporter (Volume 13, No. 2), I mentioned that I would cover new changes in the herbicide section for Extension Bulletin 237 (Pest Management Recommendations for Field Crops - 1998). For those of you viewing this newsletter on my web site, this guide is available from any county Extension office in Maryland for $7.00, or through the University of Maryland Agricultural Duplication and Distribution Services (301-403-4263).

The guide is actually very user friendly. In the herbicide section, crops are listed alphabetically (corn, forages, grain sorghum, small grains, soybeans, sunflowers and tobacco). Within each crop, we list compounds by use pattern (preplant incorporated, preemergence and postemergence). Then, within each use pattern, herbicides are listed alphabetically (ex. Corn - preplant incorporated has Dual, Eradicane, Frontier and Sutan). Also, we've highlighted alternate sections in all tables and in the text in order to make it easier to read.

The first three tables in the herbicide section are very important. The first table lists all of the package-mix products available in our region and what is contained in them. For instance, Authority Broadleaf is a 56.3 % dry flowable material. It is a mix of Authority and Classic, containing 0.469 + 0.094 lb/gallon of each product, respectively. The manufacturer is FMC. The next table lists all of the single active ingredient materials, their common name and their mode of action. If rotating products with different modes of action, this table can tell you if products are different or not. Finally, the third table lists rain free requirements for many of our postemergence herbicides. How many times do we get calls on this! This table alleviates the need to consult a product label.
 

We've updated the table on grazing and forage restrictions for corn herbicides (page 27). This was extremely important this past year throughout the state where droughty conditions occurred. The rotational crops table (pages 28 - 31) has also been updated to reflect changes in current labels as of last Fall. Once again, instead of having to sort through a product label guide, the information is at your fingertips in this guide.

New entries in the corn section include the following:
    Touchdown - new knockdown herbicide from Zeneca
    Python - was called Broadstrike WDG last year. Python is Broadstrike.
                   The single product allows you to mix it with your product of choice.
    Dual II/Bicep II - throughout the text all Dual and Bicep entries have been changed to Dual II and Bicep II
    Accent, Basis, Basis Gold, Beacon, Exceed, etc. -all post entries have been updated to reflect current tank-mix partners
    Liberty - updated to reflect use on Liberty-Link or GR hybrids
    Poast Plus - updated to reflect use on Poast Protected or SR hybrids

We've added and updated two other tables. The table of page 50 lists the different preemergence corn herbicides and the maximum corn and weed size they can be used on. The table on page 51 lists the approved tank mix partners for postemergence herbicides. Once again, these two tables are very handy as reference tools.
 

One table in for Forages section that is very helpful appears on page 66. It the grazing, feeding and harvesting restrictions table. I get a lot of calls regarding the information contained in this table. In the pasture area we have the same table on page 75, which lists the grazing and haying restrictions for grass forage and pasture herbicides. We've also updated the table on rotational crop restrictions for pasture herbicides (page 76). You'll notice in this table that Ally still carries a 34 month rotational restriction for many crops.

We haven't had many changes in these sections as we've had in others. In the sorghum section, Dual and Bicep are listed as Dual II and Bicep II. Frontier is also listed as a potential preemergence herbicide. Peak and Permit have been recently added in the postemergence section.

In the small grain section, Peak has been recently added although there is a 10 month rotational restriction to planting soybeans after Peak applications. The comments section for Hoelon has been updated to reflect labeling in the states of Delaware, Maryland, Virginia and West Virginia. We've also bolded the statement in the Hoelon section that states, "Do not apply to ryegrass past the 5-leaf/2-tiller stage." We've also recently added the use of Roundup Ultra as a harvest aid for wheat.
 

We made a lot of changes in the soybean section. In the efficacy tables we added the following: Authority Broadleaf, Canopy XL, Flexstar, Raptor and Roundup Ultra. We've added Matador to Assure II and Skirmish to Classic to reflect co-marketing agreements. These changes are reflected in the soybean rotational crops table on pages 100 - 102. Flexstar, Raptor and Roundup Ultra have also been added to the postemergence overtop broadleaf herbicide rate chart on pages 103 - 107. We've also added Poast, Poast Plus and Raptor to the postemergence grass charts on pages 107 - 109. The feeding restrictions table on page 110 has also been updated.
 

In the text, we added Authority Broadleaf and Canopy XL to the preplant incorporated and preemergence sections. Rates for Dual are now given for Dual, Dual II and Dual II Magnum. We've added Touchdown, a new non-selective herbicide, to the no-till sections. In the postemergence section, we added Flexstar and Raptor. The tank-mix table on page 129 has also been updated. All Assure II entries are listed as Assure II/Matador, while all Classic entries are listed as Classic/Skirmish. Listings for Poast include Poast and Poast Plus.
 

There aren't any new changes to the sunflower section. In the tobacco section, though, we added Spartan. The common name for Spartan is sulfentrazone. It is one of the active ingredients in Authority Broadleaf/Canopy XL. Originally, Spartan was going to be available in the soybean market by itself under the trade name of Authority. It's strong points include control of morningglories, nightshade and nutsedge, as well as a variety of other grass and broadleaf weeds.
 

Finally, for those of you that made it to the last page of the weed control section, we have a table on vegetable herbicide rotation restrictions (pages 145 - 146). We've listed most of the products utilized on a variety of vegetable crops. I use this table rather extensively, since I don't work with many of the listed products and am not always familiar with their rotational restrictions.
 

As usual, once you think you've updated everything, something new occurs. One area involves the use of Exceed. Exceed is a blend of Beacon + Peak (1 : 1 ratio). Apparently, they have had some carryover problems in the upper midwest. Novartis has now split the U. S. corn market into 3 regions. We fall in region C which has a plant-back restriction of 10 months for soybeans. Pennsylvania, though, fall in region B which has an 18 month plant-back restriction for soybeans. For areas in our region which border on Pennsylvania, I personally don't feel that we would have a carryover problem, unless the soil pH's were extremely high. In response, Novartis will be introducing some new blends. One of these is called Spirit, which is a Beacon + Peak blend at a 3 : 1 ratio. This product will be geared for the central corn belt (including PA and MD) and will have a 10 month rotational restriction for soybeans.
 
 

Lightning (American Cyanamid) - Pursuit + Arsenal - labeled for IR corn - 40 month rotational restriction for most vegetable
     crops

Distinct (BASF) - Banvel (dicamba) + auxin inhibitor - not labeled, maybe 1999

OpTill (BASF) - Frontier + Banvel (dicamba) - labeled - dark soils of the mid-west

Axiom (Bayer) - Pre grass herbicide + Sencor - not labeled yet - primarily controls annual grasses
    in corn and soybeans

FirstRate (DowAgro) - labeled pre and post on soybeans for broadleaves

Python (DowAgro) - was labeled as Broadstrike WDG last year

FrontRow (DowAgro) - FirstRate + Python - is available but not pushed in our region

StrongArm (DowAgro) - not labeled yet - pre use in soybeans and peanuts for broadleaves - won't be pushed here -
    potential carryover to corn

Accent Gold (DuPont) - Accent + Matrix + Hornet - labeled

???????????? (DuPont) - Accent + Banvel (dicamba) - will have - unsure when

Affinity and Aim (FMC) - not labeled - Aim used post in corn for broadleaves, Affinity used post in small grains for broadleaves

FieldMaster (Monsanto) - Roundup + Harness + atrazine - labeled

Northstar (Novartis) - Beacon + Banvel (dicamba) - not available yet - maybe 1999

Balance (Rhone-Poulenc) - not labeled yet - pre in corn - grasses and broadleaves
 

I've been getting a lot of calls lately about alfalfa. With the mild winter we've had it never went dormant in many areas (does it ever really go dormant?). What happens if you make herbicide applications to alfalfa when it has some regrowth? In 1995 and 1996 we initiated a study to examine just that. We took a 2-year old stand of alfalfa and made applications in late March when the alfalfa had 2 to 4 inches of growth. Applications were made to the same plots both years. During the first year of the study, first cutting data showed a decrease in weight where Gramoxone (1 pint and 1.5 pints) was used. A 12 oz. use rate did not affect yield. Sencor also lowered first cutting yields. By the fourth cutting, plots that received 1.5 pints/A of Gramoxone as well as the Sencor treated plots yielded lowest among all treatments. We did not see any yield effects from Sinbar or Pursuit. In the second year of the study, the high rate of Gramoxone and the Sencor treated plots continued to yield poorly throughout the season. What was interesting were the Sinbar treated plots. Cuttngs made through the season showed a decline in weight. Bottom line - these products can affect yield of alfalfa if applied when dormancy has broken. If you need to choose a product I would consider the 12 ounce/acre use rate of Gramoxone or Pursuit.