Does Corn have an expiry date?

Many of us would not drink milk past the expiry date, maybe on a dare but even then many of you are probably a little uneasy with just the thought of this. As corn harvest is slowed down due to weather or full elevators I get that same uneasy feeling I get thinking of drinking spoiled milk. In 2010 we planted our corn early and had great heat and rains throughout the summer in much of the corn producing areas of Ontario and Quebec and yet we are somewhat surprised that the standability is starting to weaken. Could it be that we have went past the expiry date on corn stalks and roots?

I would say yes. Current moisture levels are below 20% and the corn was fully mature (black layer) over a month ago, so the plant has been dead for a while. Dead plant material rots. If you add moisture (heavy dews, frequent rains even frost) it rots faster, plain and simple. Add high winds and rotting stalks break. One of the main differences I see in traveling from a Western corn area (mid west US) to an Eastern corn area is the higher level of moisture and therefore rot organisms that the corn plant must survive. In the East our expiry date is less than the West. Also, how the plants partitions its energy resources (sugars) – yield or plant health affects the expiry date of corn. If every plant only has one 2 gallon pail of energy to use where is it going to use it (ex. 1/2 gallon for stalks, 1/2 gallon for roots and 1 gallon for grain) each hybrid is different on how it partitions its 2 gallon bucket. Generally, the very high yielding genetics put more of its bucket into grain and the stalks and roots may run out as we go later into the season (shorter expiry date). Average yield with consistent standability may use more of its 2 gallon bucket for stalks and roots and therefore stand longer but yield less (long expiry date).

So what do I do as a grower? Harvest your short expiry date hybrids early to maximize the yield of those hybrids. This fall select a portfolio corn genetics that have long and short expiry dates.

Have a safe harvest.

Source: http://nkcropbarometer.wordpress.com/

Harvest Tips for Mouldy Corn

Some area’s in Ontario are seeing a higher levels of ear mould this year. I have included the harvest tips used in previous years.

First using the inserted picture determine if you are at risk. A quick method of determining if you are at risk includes scouting 100 plants from the field (5 areas of 20 ears each). Fields with 25 % of the ears having mould growth should be harvested sooner rather
than later.

A) Prioritize your corn harvest and storage. If producers have 2009 crop corn still left on the farm it is important to not mix it with potentially mouldy corn from this harvest. Livestock producers, especially hog, will want to scout fields, sample and test for mycotoxins in order to store their cleanest corn for feeding purposes. Cash croppers are advised that the same process of keeping clean corn segregated from mouldy corn may result in some increased marketing opportunities over the upcoming months.
B) As a general rule, harvest infected fields early. Mycotoxin levels have the potential to build the longer you leave the corn in the field. Once corn moisture is below 18%, mould fungi become dormant and cease to produce mycotoxins.
C) High temperature drying stops mould growth and mycotoxin production but does not reduce mycotoxins already present. Optimum temperature for mould growth is 28oC; mould stops growing at >30 degrees C. Quick drying is preferred over low heat drying. Be wary of low temperature in bin dryers for mouldy corn and be sure proper ventilation requirements are met for storing dry corn.
D) Leave tip kernels attached to the cob if possible by running the combine at full capacity with concave settings open and cylinder speed set low. Screens on the bottom of the grain elevator, the bottom of the return elevator and on the unload auger will also help screen out the fines.
E) Set the combine to provide high levels of wind to blow out the lighter infected kernels. Gibberella ear rot infection results in kernel damage. As noted above, cob pieces and the fines (kernel tips and red dog) contain higher concentrations. Be careful combine
adjustments do not result in kernel damage. The sample could be downgraded and increase potential storage problems.
F) Additional post-combine grain cleaning with rotary screen type cleaners has been shown to be effective in reducing mycotoxin levels in the remaining grain. This
method has the most significant impact on grain samples with low to moderate mycotoxin levels.

Check your fields before you harvest and develop a plan if you do see ear mould infection. Have a safe harvest.

Source: http://nkcropbarometer.wordpress.com/

First Documented Case Of Pest Resistance To Biotech Cotton

A pest insect known as bollworm is the first to evolve resistance in the field to plants modified to produce an insecticide called Bt, according to a new research report.

Bt-resistant populations of bollworm, Helicoverpa zea, were found in more than a dozen crop fields in Mississippi and Arkansas between 2003 and 2006.

"What we're seeing is evolution in action," said lead researcher Bruce Tabashnik. "This is the first documented case of field-evolved resistance to a Bt crop."

Bt crops are so named because they have been genetically altered to produce Bt toxins, which kill some insects. The toxins are produced in nature by the widespread bacterium Bacillus thuringiensis, hence the abbreviation Bt.

The bollworm resistance to Bt cotton was discovered when a team of University of Arizona entomologists analyzed published data from monitoring studies of six major caterpillar pests of Bt crops in Australia, China, Spain and the U.S. The data documenting bollworm resistance were first collected seven years after Bt cotton was introduced in 1996.

"Resistance is a decrease in pest susceptibility that can be measured over human experience," said Tabashnik, professor and head of UA's entomology department and an expert in insect resistance to insecticides. "When you use an insecticide to control a pest, some populations eventually evolves resistance."

The researchers write in their report that Bt cotton and Bt corn have been grown on more than 162 million hectares (400 million acres) worldwide since 1996, "generating one of the largest selections for insect resistance ever known."

Even so, the researchers found that most caterpillar pests of cotton and corn remained susceptible to Bt crops.

"The resistance occurred in one particular pest in one part of the U.S.," Tabashnik said. "The other major pests attacking Bt crops have not evolved resistance. And even most bollworm populations have not evolved resistance."

The field outcomes refute some experts' worst-case scenarios that predicted pests would become resistant to Bt crops in as few as three years, he said.

"The only other case of field-evolved resistance to Bt toxins involves resistance to Bt sprays," Tabashnik said. He added that such sprays have been used for decades, but now represent a small proportion of the Bt used against crop pests.

The bollworm is a major cotton pest in the southeastern U.S. and Texas, but not in Arizona. The major caterpillar pest of cotton in Arizona is a different species known as pink bollworm, Pectinophora gossypiella, which has remained susceptible to the Bt toxin in biotech cotton.

Tabashnik and his colleagues' article, "Insect resistance to Bt crops: evidence versus theory," will be published in the February issue of Nature Biotechnology. His co-authors are Aaron J. Gassmann, a former UA postdoctoral fellow now an assistant professor at Iowa State University; David W. Crowder, a UA doctoral student; and Yves Carrière, a UA professor of entomology. Tabashnik and Carrière are members of UA's BIO5 Institute.

"Our research shows that in Arizona, Bt cotton reduces use of broad-spectrum insecticides and increases yield," said Carrière. Such insecticides kill both pest insects and beneficial insects.

To delay resistance, non-Bt crops are planted near Bt crops to provide "refuges" for susceptible pests. Because resistant insects are rare, the only mates they are likely to encounter would be susceptible insects from the refuges. The hybrid offspring of such a mating generally would be susceptible to the toxin. In most pests, offspring are resistant to Bt toxins only if both parents are resistant.

In bollworm, however, hybrid offspring produced by matings between susceptible and resistant moths are resistant. Such a dominant inheritance of resistance was predicted to make resistance evolve faster.

The UA researchers found that bollworm resistance evolved fastest in the states with the lowest abundance of refuges.

The field outcomes documented by the global monitoring data fit the predictions of the theory underlying the refuge strategy, Tabashnik said.

Although first-generation biotech cotton contained only one Bt toxin called Cry1Ac, a new variety contains both Cry1Ac and a second Bt toxin, Cry2Ab. The combination overcomes pests that are resistant to just one toxin.

The next steps, Tabashnik said, include conducting research to understand inheritance of resistance to Cry2Ab and developing designer toxins to kill pests resistant to Cry1Ac.

Although preparation of this article was not supported by organizations that may gain or lose financially through its publication, the authors have received support for other research from Monsanto Company and Cotton, Inc. One of the authors (B. T.) is a co-author of a patent application filed with the World Intellectual Property Organization on engineering modified Bt toxins to counter pest resistance, which is related to research published in 2007 (Science 318: 1640-1642. 2007).

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Technology Protects Cotton from Caterpillar's Appetite

The furry-looking insects start their development smaller than the head of a pin, but the caterpillars soon develop an appetite for cotton as big as the crop.

To demonstrate the insects' destructive power, Clemson University entomologist Jeremy Greene planted two cotton varieties -- one genetically modified to provide protection from caterpillars, one not -- in a demonstration field at the Edisto Research and Education Center.

The non-protected cotton was planted in a pattern that spelled the word "Tigers." Aerial photographs taken near harvest show that while the genetically modified crop survived intact, the unprotected plants provided three square meals a day for the crop-hungry herbivores.

The demonstration crop was planted in late May last year and grew through the summer.

"We wanted to show the kind of damage caterpillars can do when they're allowed to eat unprotected cotton freely," Greene said.

Cotton is a multimillion dollar crop in the Palmetto State involving hundreds of farms and thousands of jobs.

Nearly all cotton varieties planted in South Carolina contain genes found in the naturally occurring Bacillus thuringiensis, or Bt, that help the plant make its own insecticide.

Bt cotton is genetically modified with specific genes from Bacillus thuringiensis. Think of it as in-plant insecticide, Greene said. This technology has been commercially available since 1996, but improvements over the years have enhanced the control of major pests.

The plant makes the proteins just like the bacterium does. The particular strain of Bacillus thuringiensis available in cotton, which was planted for the demonstration, works only on immature lepidopterans, or caterpillars. Lepidoptera is the insect order for moths and butterflies. The toxic proteins have no ill effects on other organisms.

"During 2010, we had a very high population of bollworm that infested cotton acres at the Edisto research center," Greene said. "We planted a non-Bt variety where you see the word 'Tigers' and a two-gene Bt cotton where you see the fluffy white cotton lint."

The striking difference in appearance is due to bollworms eating all of the green cotton bolls in the non-Bt variety that did not have protection from the insects.

Greene applied no insecticides to control caterpillars in this field, so the difference between the Bt and non-Bt varieties is illustrated clearly.

A color-coded yield map, produced by precision agriculture specialist Will Henderson at the Edisto center, illustrates the crop after harvest using one of the center's pickers that is equipped with a yield monitor. The map shows "good" yields in green and "bad" yields in red.

The damage potential of important lepidopteran species, such as bollworm, is not new, Greene said. Moths have flown into fields, laid eggs and hatched as injurious caterpillars for decades.

Transgenic Bt technology and its improvement over the years are relatively recent advances that represent effective, economical and environmentally friendly control of these insects in agriculture, he said.

"We know what they can do to non-Bt cotton versus Bt cotton -- the photographs speak for themselves," Greene said.

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