GNN120604

Page 1

Volume 38, Number 12 | June 4, 2012

$4.25

PRACTICAL PRODUCTION TIPS FOR THE PRAIRIE FARMER

www.grainews.ca

Don’t use desiccants to hasten maturity When a pre-harvest dessication is necessary, keep in mind that it won’t speed up maturity BY ANGELA LOVELL

D

esiccants are designed to quickly dry down the crop, as well as any green weedy material growing in the crop that might otherwise hamper harvesting operations. “It’s a common misconception that herbicides put on prior to harvest, whether it’s a desiccant or something like glyphosate, will hasten maturity — which is not the case,” says Clark Brenzil, provincial weed specialist with the Saskatchewan Ministry of Agriculture. “In large part what you are doing is trying to address some of the harvest issues that occur when you have an indeterminate growth habit in a plant,” says Brenzil. “Typically that is going to be for a broadleaf crop, and pulse crops tend to be the most commonly desiccated.” In indeterminate plants, such as pulses, flowers are produced at the bottom and continue to be produced all the way up as the plant grows. This results in mature pods at the bottom of the plant and greener material at the top. “The idea with desiccation is to dry out that green material very quickly so that you can get in there and harvest

the mature pods down at the bottom,” says Brenzil. Crop desiccants such as Reglone are contact herbicides that interfere with photosynthesis. This causes the plants’ cells to break down and release the liquid contents, allowing plant material to dry down rapidly. Water droplets can often be seen pooling on the leaf surfaces shortly after application of desiccants.

GLYPHOSATE Although glyphosate products are not desiccants, it’s a common misconception that glyphosate applied prior to harvest will act as a desiccant. “There is often a blurring of the term,” says Brenzil. “Farmers will often say ‘we’re desiccating with glyphosate’ and that’s not the case. Glyphosate kills plants; then it’s left to Mother Nature to dry them down.” More correctly, says Brenzil, farmers use a pre-harvest application of glyphosate to control perennial weeds. “The glyphosate circulates in the plant and gets down to the roots and controls that perennial weed,” he says. “Pre-harvest is a particularly good time of year to achieve that, particularly the further north you go.”

Incorrect timing of pre-harvest herbicides can actually have a negative impact on maturity, says Brenzil. “The maturation process is more than just the dry-down of the plant. The first step in maturation is the filling of the seed and then once the seed is filled, it starts going through that drying down process,” he explains. Herbicides applied too early can interrupt the process of seed filling, resulting in yield loss. There is also a danger of herbicide residue ending up in the seed, a particular concern when using glyphosate, for which some European countries have set very low maximum residue limits in pulse and other crops. “Glyphosate is a systemic product, which means that once it enters the plant it will get into the circulation system and move through the plant to the same places that the sugars are going, which are called sinks,” says Brenzil. “The sink at the pre-harvest timing is the seed. So basically what you are doing by applying early is taking what is applied to the surface of the leaf and putting it right into the seed.” For this reason glyphosate should not be used as a pre-harvest application when growing pulse crops for seed the following

PHOTO: ROBERT KLEWCHUCK, SYNGENTA

This 2010 lentil crop was desiccated with Reglone in 2010. The photo shows a complete dry-down, including the lentil stems. year, because of an increased risk of poor emergence.

DESICCANTS AND FROST Desiccants are contact herbicides which only have impact on the tissues they come into contact with. They do not move systemically through the plant. Another myth about pre-harvest treatments, whether desiccants or glyphosates, is that they can protect a crop from the damage caused by a frost, similar to swathing. “When a crop is swathed there is still some subsequent matura-

In This Issue

Publications Mail Agreement Number 40069240

tion of the seed as the swath dries, but with herbicides you are simply killing the crop prematurely,” says Brenzil. “Desiccation could be seen as the chemical equivalent to frost and performs roughly the same process except it is ice crystals that form within the cells that puncture membranes and release the cell contents to the air. It is doubtful that a crop treated with glyphosate will be dry enough when a predicted frost materializes to protect it at all. Producers are just throwing away their money

» CONTINUED ON PAGE 4

Wheat & Chaff ..................

2

Features ............................

5

Crop Advisor’s Casebook

12

Columns ........................... 13 Cattleman’s Corner .......... 19 Machinery & Shop ............ 39

Combine consultant says we’re setting them wrong T:10.25” SCOTT GARVEY PAGE 39

COULDA

SHOULDA

WOULDA

Keeping those old bins in use

FarmLife ............................ 47

RON SETTLER PAGE 37

DID PROSARO T:3”

Visit us online for Demonstration Strip Trial (DST) results at BayerCropScience.ca/ ItPaystoSpray BayerCropScience.ca/Prosaro or 1 888-283-6847 or contact your Bayer CropScience representative. Always read and follow label directions. Prosaro® is a registered trademark of Bayer. Bayer CropScience is a member of CropLife Canada.

C-53-06/12-BCS12009-E


Turn static files into dynamic content formats.

Create a flipbook
Issuu converts static files into: digital portfolios, online yearbooks, online catalogs, digital photo albums and more. Sign up and create your flipbook.
GNN120604 by Farm Business Communications - Issuu