An Irritating Fact of Life
Thursday, April 1, 2010
filed under: Birds
Blackbirds continue to be one of the reasons why some farmers in the prairie pothole region of the Dakotas choose not to grow sunflower. It is one of those production problems that the leaders of the sunflower industry would love to pass off to another commodity. But that is not going to happen, and the reality is that blackbirds continue to be a sunflower production issue year in and year out.
Sunflower growers are not alone. Blackbirds do an estimated $200 million damage to a range of crops, including grains, oilseeds, vegetables and fruits. Feed loss, stress on cattle and disease concerns at the nation’s dairies and feedlots due to blackbird movement and contamination continue to be of great concern to those industries.
The region’s sunflower growers will again get assistance in the 2010 season from USDA Wildlife Services (WS) in harassing blackbirds out of sunflower fields.
The first line of defense is controlling cattails in wetlands with standing water. Growers can spray their own wetlands or sign up with USDA-WS and have the agency do it. The one problem with USDA-WS is that the agency usually has more wetlands to spray than it has funding. The agency has concentrated most of its control work in east central and north central North Dakota, where the majority of wetlands exist. The agency uses a helicopter to avoid spray drift and to control the irregular contours of most wetlands. However, fixed-wing airplanes are effective, and farmers are urged to control those wetlands that are well known to them as an annual bird roost. Cattails can be sprayed from mid-July to the first frost. There are a number of aquatic herbicides registered.
Dr. George Linz of the USDA-APHIS-WS National Wildlife Research Center has found that eliminating cattails in a wetland can pay dividends for five years or more. Linz says it is necessary to spray after mid-July when all of the new growth is above the water level. It can also have a first-year benefit if sprayed in July, according to Linz.
Phil Mastrangelo of USDA-APHIS-WS coordinates the government spraying of cattails. Growers must complete an application. (That application can be obtained on the National Sunflower Association website at www.sunflowernsa.com/growers/blackbirds or by calling Mastrangelo’s office at 701-250-4405.) Mastrangelo says about 4,500 acres of cattail-infested wetlands are sprayed annually in North and South Dakota. “This is a small percentage of the total wetlands; but by keying in on the problem wetlands, it has made a significant difference for producers in those areas,” according to Mastrangelo.
The second line of defense is a “boots on the ground” campaign started in 2006. USDA-WS employed seven parttime seasonal staff to deliver and station loaner propane cannons when Dakota fields were being hit by blackbirds. Minnesota started a pilot program in 2009 in several counties.
The cannons are equipped with automatic timers that turn off the noise mechanism at night to conserve propane. The sequence of explosions can be easily changed to minimize the risk of blackbirds becoming habituated to the noise.
Mastrangelo says farmers who have been using these cannons are finding pretty good success in keeping birds out of their fields. The key is to get the cannons in the field early before the birds get habituated to using that field as a major food source.
Federal and state laws allow producers to shoot birds that are damaging their crops; the addition of lethal control reinforces the effect of frightening devices.
USDA has been buying cannons each year, but still finds the demand to be greater than the supply. Growers can add timers to their own cannons and WS staff can be of assistance. Mastrangelo is impressed how grower innovations have added to the effectiveness of cannons, such as by getting them above the field canopy and adding hollowed-out barrels to intensify the noise.
In 2010 Mastrangelo will add an eighth seasonal employee to increase service delivery to sunflower growers. But what happens when the migrations come through the flyway, and 50,000 birds decide to use your field as their primary feeding source?
In those cases, Mastrangelo sends out a mini army of four to five seasonal and full-time employees to harass these huge flocks. “Generally, these large flocks are keyed into migrating, and we just give them some additional reasons to do so,” he says. “It has worked quite well, especially if the grower has left a driving lane in the middle of the field for a four-wheeler or pickup.” In a few extreme cases, a helicopter has been brought in. The key message, Mastrangelo states, is that “we are not going to let a grower hang out there alone, trying to fight a huge flock of birds and take huge losses.”
Chemical bird repellents have been on the market for several years. There are two registered bird repellent products on sunflower: Bird Shield™ and Flock Buster™. Both consist of natural ingredients. The challenge with any repellent, according to Linz, is the weather and the difficulty of getting the product on the face of the sunflower head. Rain often will dilute the impact of a repellent.
The other factor is that the sunflower head on most hybrids begins to bend down after petal drop. If the repellent is a taste-aversion product, the chemical has to get on the face of the head. There is only a small part of each seed in the tight head that is exposed. Linz hopes that the elevated ground sprayers discussed in the January 2010 issue of The Sunflower (“Spraying at Bloom with a Ground Rig”) might be able to do a better job in this regard with extra volume of water.
The manufacturers of Flock Buster have made formulation changes by increasing one of the scents. They report better 2009 results with the higher concentration. They’re also testing adjuvants and stickers to determine if the product’s field life can be enhanced.
USDA will be testing an unregistered experimental product this summer. Caged tests in 2009 were very favorable, but a hand sprayer was used to ensure adequate coverage on the face of the ’flower heads.
Linz reports that there is a strong push nationally to identify an effective blackbird repellent for a host of crops. “This problem is getting more intense and is hitting crops with very high value throughout North America,” he says.
The other key element in the bird battle is getting the crop off as soon as possible. The use of desiccants can be a very effective tool. Kixor®, labeled as Sharpen™, has been tested for several years, is now fully registered, and will be available in the 2010 season. Other labeled products include sodium chlorate (Drexel Defol®), glyphosate and gramoxone (Paraquat™).
Sharpen’s advantage is that it is faster acting than glyphosate. Also very important is that it doesn’t disrupt plant cells in the same way as Paraquat, says North Dakota State University weed scientist Kirk Howatt. “Many growers gave us examples of sunflower that seemed to soak up water after spraying Paraquat,” according to Howatt. “Our results indicated that plants can rehydrate regardless of desiccant treatment or natural senescence; but plants may be influenced by this process for a longer period because of the rapid action of Paraquat.” It is that aspect of Paraquat that allows the plant to rehydrate during an extended wet period. The rehydration of large, heavy heads has led to increased stalk breakage.
One challenge when desiccating is determining physiological maturity. Labels say to desiccate when seed moisture is at or less than 36 or 35% moisture (depending on the product). There currently is not an accurate seed moisture reader available to do a quick test.
Research recently completed by Burton Johnson (NDSU) and Russ Gesch (USDA-ARS, Morris Minn.) indicates that physiological maturity varies with the hybrid; but in all cases, maturity is reached at 35%. However, in several instances hybrids were mature at 40% moisture and sometimes as high as 44%.
It is mandatory to follow the label. But determining maturity is a tricky issue, and Johnson’s research points to a reasonable cushion on the top side of desiccation triggered at 35% seed moisture.
Research has proven that desiccated sunflower can be harvested as much as 21 days earlier compared to the check. That all depends on air temperature and sunlight. But getting a seven-day harvest advantage can be huge when birds are an issue or if winter wheat is scheduled to be planted into the sunflower stubble.
Levels of Damage
Does the harassment of blackbirds make any difference in overall damage? Linz and Mastrangelo think it does, and survey data confirm that belief. Since 2006, when the “Boots on the Ground” began, the percent damage has declined, with the exception of 2008.
But the trend is going in the right direction, says Reg Herman of Brinsmade, N.D., a National Sunflower Association board member who farms in the heart of the wetland area. Field surveys conducted by volunteers each year at the end of September found only one field in each of North and South Dakota with damage exceeding 25%.
Linz identifies a couple reasons for the better effectiveness of harassment today compared to 10 years ago. First, the techniques are better and the delivery system designed by USDA is much more effective than former programs.
Second, with the explosion of corn acres in the Upper Midwest, blackbirds have a good alternative feeding source when being harassed, says Linz. “When under pressure in sunflower fields, blackbirds go to corn for protection and food,” he points out. His surveys of adjoining corn fields confirm that.
“I do find damage in corn fields, but it is generally harder to find. Also, with corn yielding 5,000 to 6,000 lbs/ac, growers do not experience the same kind of yield impact as with sunflower at 2,000 lbs/acre,” Linz remarks.
The National Sunflower Association will be informing growers by mail and on its website of numbers to call for assistance, starting in July. — Larry Kleingartner