Saturday, December 29, 2012

Urbanization Hurting Bumblebee Populations

Paved roads and development in rural areas is adversely affecting ground-nesting  bumblebees, an important native pollinator, according to research at The University of Texas at Austin and the University of California, Berkeley.

"Honey bees are declining precipitously, and wild bees have also been exhibiting population declines across the globe. Native bees provide critical pollination services for fruit, nut, fiber and forage crops," says professor Shalene Jha, lead author of a study suggesting management strategies that reduce the local use of pavement and increase natural habitat within the landscape could improve nesting opportunities for wild bees and help protect food supplies around the world.

The study also suggests that increasing the number of species-rich flowering patches in suburban and urban gardens, farms and restored habitats could provide pathways for bees to forage and improve pollination over larger areas.Animal pollination is estimated to be worth over $200 billion in global crop yields.

In addition to finding that pavement negatively affects the bees, the scientists discovered that:

> Bees will move longer distances to find patches of flowers that are rich in species; it's not floral density that determines how far a bumblebee will fly, but floral diversity.

> Bees will also forage further away from their home nest if the surrounding landscape is less heterogeneous.

"In combination with earlier work showing that bumblebees have become rare in agricultural landscapes, our study suggests that farmers could promote these valuable pollinators by diversifying crop types and by planting cover crops and flowering hedgerows to enhance floral diversity," says environmental scientist Claire Kremen of the University of California, Berkeley.

Bumblebees nest in the ground, and each colony contains a queen and a force of workers. As with honeybees, all of the bumblebee workers are sisters who spend some of their time flying around searching for flowers from which to collect pollen and nectar to feed the larvae back in the hive.

Unlike honeybees, which are not native, bumblebees do not make harvestable honey. They do, however, provide important pollination services to plants.

Claire Kremen, University of California, Berkeley; 510-367-2100
Shalene Jha, University of Texas at Austin; 248-719-5766

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Artwork: Bumblebee

Tuesday, November 20, 2012

Protecting Stored Grain Through Fall and Winter

As most dryland corn producers know, the only defense against mycotoxin contamination in corn is to manage the grain moisture content and grain temperature to minimize mold growth in the grain. Recommendations to protect stored grain:

Dry dryland corn down to 13% moisture if it’s to be stored for more than a month.

Run aeration fans whenever the air temperature was 10 degrees cooler than the grain temperature since the rate of mold growth is slower at cooler temperatures.

Cool stored grain down to 30°F (plus or minus 5 degrees) to stop mold growth. If the grain has not been cooled to the recommended temperature for late fall and winter, do so soon, especially if the grain will be kept into the new year.

In fall and winter, grain next to the bin wall will be cooled while grain in the center of the bin will stay warmer. The difference in temperature can result in convection air currents migrating through the grain (Figure 1). The warmer air in the center of the bin rises and the grain next to the cold bin wall sinks. When the warm rising air encounters the colder air at the top of the bin, the escaping air can go below the dew point temperature of the rising air and deposit moisture on the grain. This can create a wet spot in the top-center of the bin.

If the grain is warm enough for microbial activity, a hot spot can form and molds can grow, even in winter. This includes molds that can produce mycotoxins.

Run the aeration fan(s) at least once a month when the humidity is low and the ambient air temperature is 30 to 35 degrees. To conduct a preliminary check on grain quality, start the aeration fan(s), then climb up and lean into the access hatch. If the air coming out of the hatch is 1) warmer than you expected, 2) has a musty order or 3) If condensation forms on the underside of the bin roof on a cold day, continue to run the fan(s) long enough to push a temperature front completely through the grain.

A rule of thumb is, the time (hours) to push a temperature front through a bin of grain is 15 divided by the airflow-cubic-feet per minute per bushel cfm/bu.

For example, a bin used for drying grain should be able to produce about 1.0 cfm/bu so it would take about 15 hours to push a temperature front through the grain (15/1 = 15). In another example, a bin equipped with a fan able to push only 0.3 cfm/bu could push a temperature front through in 50 hours (15/0.3= 50).

Source: Tom Dorn, Extension Educator, Lancaster County, University of Nebraska–Lincoln

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Artwork: Farmers Send Corn Via Rail Cars to a Local Silo for Storage by Howell Walker

Wednesday, October 24, 2012

New Potatoes Rich in Carotenoids

Scientists with USDA's Agricultural Research Service (ARS) are breeding new yellow-fleshed potatoes with carotenoid levels that are from two to 15 times higher than those of the popular Yukon Gold variety.

Carotenoids are of keen interest because they appear to protect against age-related macular degeneration and perhaps against cataract formation.

ARS plant geneticist Kathy Haynes discovered wild potatoes with intense yellow flesh that have about 23 times more carotenoids than white-flesh potatoes. By crossing these wild potatoes with cultivated types, Haynes  developed high-carotenoid potatoes for commercial markets.

Haynes and her colleagues introduced a new potato named "Peter Wilcox" in 2007 which has become popular in niche markets. The overall carotenoid levels in the purple skinned and yellow fleshed potato are more than 15 percent higher than those in Yukon Gold.

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Artwork: Peter Wilcox potatoes. Photo by University of Florida.

Wednesday, August 22, 2012

Sugar is Death to Aphids

A treat for humans, sugar can be deadly to aphids.

Agricultural researchers are now exploiting this vulnerability as an insecticide-free way to control insect pests.

"There is an urgent need for new strategies for insect control, because insects are developing resistance to traditional broad spectrum insecticides," says professor Angela Douglas of Cornell University.

Douglas and fellow scientist Georg Jander are genetically engineering plants to protect themselves by increasing the sugar in their sap.

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Wednesday, July 18, 2012

Drought Causing Nutrient Deficiencies

Dry conditions persisting across much of the Midwest U.S. are causing nutrient deficiency problems. Unfortunately, only rainfall will fix some of these problems.

Foliar or soil application of nutrients is not recommended, according to University of Illinois assistant professor of crop sciences Fabián Fernández.

Many corn fields show potassium deficiency even though adequate fertility is present in the soil. Why is potassium deficiency showing up in corn more often than any other nutrient deficiency?

“The most likely reason is that, early in development, corn takes up larger amounts of potassium than of nitrogen and phosphorous,” Fernández explains. “Soon after the V12 development stage, corn has already taken up half of all the potassium it will need.”

In contrast, nitrogen and phosphorus are taken up until sometime after the dent stage (R5). Unlike nitrogen, which moves freely over large distances in the soil solution, phosphorous and potassium can move only a few millimeters at most; thus, when the soil dries out, their position makes them unavailable to the crop.

The reason this happens is that pore space in the soil contains water and air. Plant-available potassium ions are dissolved in the soil water or attached to soil particles ready to come into solution as the plant needs them. When there is sufficient water in the soil, the potassium ions dissolved in water have to travel (by diffusion) only a short distance to be taken up by the crop.

As the soil dries out, the pore space fills with air. The potassium ion has to travel across a larger distance to reach the root because it cannot diffuse through air. Increased diffusion time can cause important reductions in potassium availability to corn during vegetative stages when potassium demands are large.

“Under dry conditions, the soil is unable to keep up with the crop demand even though there might be sufficient potassium in the soil,” Fernández explained.

While there is nothing that can be done to solve the current drought problems, this year has taught producers a number of important lessons.

“For the future, I recommend that we minimize the effect of drought by ensuring that any water in the soil is protected to be used by the crop,” Fernández said. “This year, some farmers have seen firsthand how much water weeds can take up when not treated early in the season.”

Similarly, too much tillage in some situations has caused unnecessary water evaporation from the soil and those fields are running out of water sooner than those that were managed more carefully.
Source: University of Illinois

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