Managing “Bad Grass” (Part 2)
I have been meeting and talking with corn farmers for nearly 10 years in my profession as an agronomist, and I find it amazing to see how ordinary, corn farmers react to some of the latest technologies in corn production. When farmers thought that 3- or 4-tonner corn variety was good enough, they were surprised that hybrid technology could easily double that yield. Nowadays, we hear Gawad Saka awardees for corn hitting or even surpassing the 10 MT/ha level. What’s more, farmers are now offered more options to buy hybrids that protect themselves from one of the most serious pests of corn like the Asiatic corn borer (ACB). These hybrids give farmers efficiency, convenience, and most importantly, better control of things in the cornfield.
With such developments, solutions for weed problem should not be that far. While there are plenty of management options, almost all are characterized by limited window of application, crop damage (burn), highly manual, and expensive. Some could even be described as simply ineffective. Just as the ACB problem has been pestering our farmers, weeds are perennial headaches.
So, is there something new to combat weeds in your cornfield? Rather, the right question is: What is this new technology in corn that makes weed control so easy and effective?
USING GLYPHOSATE ON CORN
There are many herbicides for corn being marketed in the Philippines. Among the most common are atrazine, pendimethalin, paraquat, and 2,4-D. The first two are generally recommended only as pre-emergent herbicides – meaning to be sprayed on the field prior to seedling emergence. They target selectively weed seeds and seedlings, hence window for spraying is confined to the very first few days after planting (within 3 days) and cannot control other older weeds.
Paraquat and 2,4-D, on the other hand, are considered post-emergent herbicides. They are sprayed at a much later date after planting where the weeds appear to grow competitively with the main crop. Weeds are controlled selectively but farmers are often not satisfied with the results. Phytotoxicity such as crop burn are usually observed due to misuse or lack of precision in application. As a result, these herbicides are not being adapted consistently.
In the recent years, another herbicide called glyphosate is being used for no till management in corn. Being a broadspectrum, non-selective, and systemic herbicide, this is preferred by farmers in newly opened grass areas and orchard where field crops are planned to be grown. Glyphosate can kill most plant types which include grasses, perennials, and woody plants. When a plant is sprayed with glyphosate, the herbicide is absorbed through the leaves and the soft tissue of the stem. In a matter of days, treated plants die.
GLYPHOSATE-READY CORN
Because of the high sensitivity of plants, including corn, the use of glyphosate has been limited to being a pre-plant or pre-crop emergent herbicide. In some cases, it can be a crop desiccant applied shortly before harvesting. But with the rapid advancement of biotechnology, certain types of corn have been developed to tolerate herbicides such as glyphosate. In short, even if this herbicide is applied at the same time to both the corn crop and weeds, the glyphosate-tolerant corn will have very little or no damage at all.
Glyphosate-tolerant corn (event NK603) was primarily developed to allow the use ‘of glyphosate as a weed control strategy. It contains a special plant enzyme EPSPS that allows the plant to survive the lethal effects of glyphosate application. Just like Bt corn, the special ability of glyphosate tolerant corn was isolated from a common soil bacteriurri.9grobacterium tumefaciens (CP4 strain) and introduced into its inbred line.
Glyphosate-tolerant corn, and even soybeans, is now being grown among advanced agricultural economies such as in the United States, Argentina, China, and South Africa.
After undergoing- and passing the government-required confined trials for safety and efficacy, farmers have now another option of selecting hybrids that come with a built-in weed management solution. Hybrids such as Pioneer® hybrid 30G80 offers corn growers the best features of conventional hybrid 301380–high yield, high shelling recovery, stable performer and built-in tolerance to glyphosate herbicide accredited by the Fertilizer & Pesticide Authority (FPA). For this, weeds which can reduce corn yield by as much as 90% can now be managed.
However, some corn areas are not only plagued by weeds. They are also concerned with the Asiatic corn borers. Can these two be combined? The answer is a resounding yes! Just as the trait of YieldGard (for control of ACB) and glyphosate-ready technology were approved as effective and safe for use, technology developers have already thought of combining or stacking them together in a particular hybrid. Out in the market now are hybrids such as PioneerOO hybrid 30T80 (also called 30B80-stack) offering total protection from borers and weeds.
EASY AND CONVENIENT
Ensure you get the most of what modem technology can offer in corn production. The following is a simple guide from Pioneer:
1. Know your farm. Yields can be lowered by poor weed management.
2. Find out if your top conventional hybrid of choice had these traits. For example, 30B80 has a stacked-version 30T80 and YieldGard version 30Y80.
3. Once planted, spray any FPA-approved glyphosate herbicide for corn at 12-15 days after planting or when weeds are 1-2 inches tall. Spraying can be done over the top.
4. If weed regrowth are observed in the later stages, optional spraying is recommended at 35-40 days after planting.
5. You may contact your local Pioneer agronomist for advice.