New Race of Antrhracnose Found in Canada
March 28, 2008
Dry bean growers have been limited in the number of crop desiccants at their disposal. But Richard Zollinger, extension weed specialist with the NDSU Extension Service says that is about to change.
I am pleased to announce that after several years of testing and hard work, we will likely receive registration of Valor as a pre-harvest desiccant for dry beans, says Zollinger. And the registration should occur in March or April of this year.
Until now, growers have had to rely on Paraquat and Aim for dry bean desiccation. In 2004, registration was given for Glyphosate for weed desiccation, but not for dry bean desiccation.
Zollinger says the use rate for Valor will be 1.5 to 2.0 oz/A, and use of an MSO-type adjuvant will be mandatory.
Since Valor is not a very good weed desiccant, Valent, the manufacturer of Valor, will allow a mixture with Paraquat for weed desiccation.
Zollinger says the Valor registration was a multi-organization collaborative effort including state weed researchers, the manufacturer, and the Northarvest Bean Growers Association, with funding support from the Department of Agriculture.
Saflufenacil: An Emerging Desiccant
Zollinger also noted that BASF has released a new active ingredient called Saflufenacil. With a very fast burn-down rate, Saflufenacil is a non-phenoxy that will be registered as a pre-plant or pre-emergent herbicide in corn and soybean.
Because of its fast burn-down activity, we thought Saflufenacil might also have potential as a crop desiccant, says Zollinger. Preliminary research is promising, showing very rapid activity in dry bean (Table 1).
Zollinger indicated he would work with the Northarvest Bean Growers Association to see whether continued research into Saflufenacil as a dry bean desiccant is warranted.
Weed Control in Dry Bean
Zollinger reported on another experimental herbicide KIH-485 a pyroxasulfone from Kumiai America. KIH-485 is a pre-emergent herbicide with an unknown mode of action, says Zollinger. From a weed resistance point of view, thats really good.
The first crop registrations for KIH-485 will be in corn and soybeans in 2010. It provides season-long grass and broadleaf control with very little carryover.
Zollinger says KIH-485 not only controls foxtail, lambsquarters and redroot pigweed, but what separates it from Lasso and Dual is its control of wild mustard, kochia, nightshade, wild buckwheat, common ragweed (60-95%) and marshelder (70-99%). It does not, however, control cocklebur or sunflower.
The sunflower tolerance led us to believe there may also be some crop tolerance in dry bean, says Zollinger. Research at Colorado State University and the University of Guelph in Canada, suggested that there wasnt a high level of safety, but depending on rainfall and the time of application, we might get some pretty good dry bean tolerance out of it.
NDSU tested KIH-485 on a number of crops including dry beans, corn, wheat, oats, soybeans, field peas, lentils, sunflowers, safflower and flax.
Zollinger says their dry bean tests in 2006 showed good results without a lot of crop damage. But results in 2007 showed more significant crop damage, due in part to rainfall in the early part of the spring. We had a lot of activity and herbicide down into the root zone, so there was a lot of root uptake, he says.
Zollinger then approached some of the noted dry bean researchers in the country. They developed a protocol to use the exact same treatments on various dry bean types.
In New York, Robin Belinder found some tolerance to KIH influenced by rain events. In Michigan, Christy Sprague found tolerance influenced by rate and variety. But in Nebraska and Colorado, Bob Wilson and Scott Nissen found very poor tolerance, with nearly 100% control of dry bean in their studies.
So then we tried adjusting the rates, says Zollinger. We found that by backing off on the rate, we could still get good weed control.
Zollinger says research into KIH-485 as a dry bean herbicide will continue.
Baddest Weed in Dry Beans
What was the baddest weed in Northarvest grower fields last year? According to Zollinger, ragweed problems topped the list of weed concerns based on phone calls he received from growers during the 2007 growing season.
So how can growers control ragweed? Neither Basagran nor Raptor control ragweed. Reflex can control ragweed if the plants are small. But a new tool in the ragweed arsenal is Permit.
Permit (halosulfuron) from Gowan, is a soil-applied herbicide. Currently it is registered as a pre-emergent herbicide, but Zollinger hopes it will be registered as a post-emergent herbicide within the next two years.
Research has shown that an application rate of .5 to .67 oz/A can control large-seeded broadleaf weeds like mustard, ragweed, sunflower and cocklebur. Permit is similar to Reflex, but uses a different mode of action. It wont control lambsquarters or buckwheat, and it also has some crop rotation restrictions.
So for now, asks Zollinger, if you have a serious ragweed problem, how do you control it? I would propose using Permit as a pre-emergent herbicide, which would allow you to use Reflex post-emergent to get any ragweed that was left uncontrolled. But remember, he says, that both these products have crop rotation restrictions.
Herbicide Tolerance Problems
Zollinger also reported that ragweed populations across the country are becoming resistant to glyphosate. Growers producing soybeans in Ohio, Illinois and Missouri already have ragweed populations that are resistant to glyphosate, and last year, Kansas became the first state to confirm four weed species (waterhemp, common ragweed, giant ragweed, and marestail) that are resistant to glyphosate.
We not only have ragweed resistance to glyphosate, but also resistance to Reflex, Permit and Flexstar. So keep in mind that there is a lifetime to this chemistry. How we use it, says Zollinger, I guess is up to you.
Identifying Anthracnose in Dry Beans
Anthracnose symtoms on the leaf. Anthracnose symtoms on the petioles.
Anthracnose on the pod. Bacteria on the pod.
Anthracnose on the bean. The top rows are clean, and the bottom shows the anthracnose infection.