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Tip-back and the 2016 corn crop

Published August 5, 2016
Signs of tip-back on ears of corn.

URBANA, Ill. - Although crop condition reports and yield prospects for the 2016 Illinois corn crop continue to be good, there has been some recent discussion about unfilled ear tips and whether or not this might mean lower yields than the appearance of the crop leads us to believe, says a University of Illinois crop scientist.

Corn ears with kernels missing at the outer end of the ear are often said to have “tip-back.”

“The term is a little obscure, but the idea is that something happened to cause the ear to adjust its kernel number downward so it won’t have as many kernels to fill. That exposes the end of the ear,” says Emerson Nafziger.

The missing kernels can be aborted kernels—ones that were fertilized but stopped developing—or can be kernel initials that weren’t fertilized due to problems with the pollination process. Low sugar levels in the plant before, during, and after pollination are often associated with such loss of kernels.

“Because kernel number is closely related to yield, missing kernels on an ear suggests that yield has been lost,” Nafziger explains. “Drought stress, loss of leaf area to hail or disease, or lack of nitrogen all result in stress that lowers photosynthesis which decreases the sugar supply. So we associate low kernel numbers with stress.

“While low kernels numbers per acre and low yields do go together, it’s important in a year like this to consider the overall condition of the crop and to focus on how many kernels are present before worrying about how many kernels seem to be missing. We often see some amount of tip-back even in good years, and this may have no effect on yield if kernel numbers are still high,” he adds.

As an example, under outstanding pollination conditions in 2014, Nafziger says almost no tip-back was seen; ears were filled out to the very end of the cob. “There was much more tip-back in 2015, but kernel counts per acre and yields were as high in many areas in 2015 as in 2014. While we don’t think that having some tip-back is necessary to show that the ear had ‘extra’ room in case it was needed it, it’s much more common to see some tip-back than to see none. We certainly don’t consider tip-back to be a problem if kernels numbers are high,” he says.

Nafziger adds that what matters for yield is the number of kernels per acre that fill, along with the ability of the crop to fill them completely. “So 34,000 ears each with 16 rows of kernels and 35 kernels per row should produce yields in the vicinity of 220 bushels, even if most cobs have ‘room’ on the end for another 50 or 100 kernels. At high yield levels when all of the nutrients the plant produces go to fill kernels, having more kernels may mean that kernels stay smaller, and yield may not change much,” he says.

Nafziger says he is seeing some signs that kernel numbers in some fields may not be as high as expected. In one field on South Farm near Urbana he found tall plants and green leaves, but ears with fewer than 400 kernels per ear, or yield potential of perhaps 160 bushels per acre. In another field with similar soil planted at the same time with slightly lower population, plants were not quite as tall, stalks were larger in diameter, and ears were more uniform in size. Ears show a small amount of tip-back, but with an average of about 600 kernels per ear, this field should yield 225 bushels per acre or more, he says.

“There are no obvious reasons why similar fields planted at about the same time should have such different kernel numbers and yield potential,” Nafziger explains. “The field with lower yield potential has a number of different hybrids and most seem to show some degree of the same problem, so hybrid doesn’t appear to be the main difference. Both fields emerged well and have had good uniformity and dark green leaves from the beginning.

“Variability in ear size and placement suggests that plant-to-plant competition began early and increased during vegetative growth, eventually showing up as non-uniform ear development and lower kernel numbers. Temperatures in May and June were warm and there was a lot of sunshine. Rainfall both months was near normal, but the latter half of June was dry, which could have meant more underground competition,” he says.

The crop appears to have used a lot of resources to grow the plant, including roots as they grew deeper during dry weather in the weeks before pollination. Uniformly warm air and soil temperatures and rapid growth during that period might have meant some diversion of sugars away from ear growth and kernel set, Nafziger says. “It’s also possible that uptake of water was slightly lower in some soils due to texture or root growth and uptake, and that the crop in such soils experienced a little more stress.

“Although we can’t do anything to change kernel numbers now, it is worthwhile to visit each field to note kernel number and other plant characteristics that can help explain what happened in different fields. While the Illinois corn crop condition overall remains good, some fields may have disappointing kernel numbers even on plants that continue to look very good. Note which hybrids show this, but given that this may be a one-time phenomenon, be cautious about discarding hybrids, especially those that have been top-yielding in the past,” he adds.

Palmer amaranth and non-crop environments

Published August 5, 2016

URBANA, Ill. - Palmer amaranth (Amaranthus palmeri) has garnered much attention recently in both academic discussions and popular press releases, and with good reason, says University of Illinois weed scientist, Aaron Hager.

Among the weedy species of Amaranthus, Palmer amaranth has the fastest growth rate and is the most competitive with the crops common to Midwest agronomic cropping systems, Hager explains. Soybean yield losses approaching 80 percent and corn yield losses exceeding 90 percent have been reported in the peer-reviewed scientific literature.

“While most concern focuses on Palmer amaranth in agronomic cropping systems, keep in mind that Palmer amaranth also can become established in non-crop areas,” Hager cautions.  “Palmer amaranth populations in non-crop environments obviously do not compete with agronomic crops, but these established plants can produce seeds that ultimately find their way into crop production fields.”

Hager said that crop scientists recently verified the identification of a Palmer amaranth population growing in an area enrolled in the Pollinator Habitat Initiative of the Conservation Reserve Program. The origin of this population remains unknown, but some speculate the forb seed mixture purchased to sow the pollinator area might have been contaminated with Palmer amaranth seed. 

“Regardless of how and where a Palmer amaranth population becomes established, it remains critically important to take all appropriate steps to prevent established Palmer amaranth plants from producing seed,” Hager says. “We strongly encourage all who have established pollinator habitats with a purchased forb seed mixture to scout these areas as soon as possible. 

“If Palmer amaranth is identified, please take steps to remove these plants before viable seeds are produced on the female plants. Plants should be severed at or below the soil surface and carried out of the field. Severed plants can root at the stem if left on the soil surface, and plants can regenerate from stems severed above the soil surface,” he says.

Manage pests on your favorite trees

Published August 5, 2016
Eastern Tent Caterpillar

URBANA, Ill. – University of Illinois Extension horticulture educator Kelly Allsup cautions to watch out for insect pests on favorite landscape trees this late summer and fall. “If you don’t take necessary management actions at the appropriate time, the battle against them may be hard to win,” she says.  

Allsup provides the following information:

Tree pests like fall webworm and oystershell scale have some control management practices that can be implemented in late summer and fall.

Fall webworm (Hyphantria cunea) attacks a large number of tree species but especially hickory, ash, birch, walnut, crabapple, apple, elm, maple, oak, and pecan.

There are two generations of the fall webworm in the southern portion of Illinois. The first generation emerges in late June or July and again in August and September. In the northern portion of Illinois, only one generation emerges in August and September. As far as the overall health of the tree, only the first generation is of concern.

Pale green and yellow caterpillars with thick white hair tufts begin to hatch. They feed for several weeks in tents on the tips of the branches. They can skeletonize leaves and even defoliate trees. After six weeks of feeding, they fall to the ground or find a nice crevice in the bark to pupate.

The adults, which are a pristine white moth (with or without black dots) emerge again in August to lay white egg masses on the bottom sides of leaves. Sometimes she lays them on branches or the trunk and they look like dark brown oval knobs.  At this time, the most efficient method is to prune out webs of caterpillars, scout for, and remove egg masses.

The Pest Management for the Home Landscape says Bacillus thuringiensis var. kurstaki (Btk), among other pesticides, can be applied when caterpillars are young and tents are new for the best efficacy. This bacterial pesticide must be ingested to be effective, so open up the tents and spray on leaves inside.

Or, just let nature take its course. According to Michigan State University Extension, there are over 50 species of wasps that parasitize the eggs or caterpillar and over 30 percent of predators will devour these late-season threats. 

Oystershell scale (Lepidosaphes ulmi) begins to emerge and attack a large species of trees in early May, especially lilac, ash, privet, beech, and viburnum.

Yellow crawlers emerge to feed causing yellowing, stunted foliage, and branch die back. A second generation of this pest can be controlled when Queen Anne’s lace is blooming in August with an insecticidal soap or a summer spray of petroleum oil. Spraying the crawler stage of this pest is best because they have not yet developed the waxy coating that prevents penetration insecticide. Heavily infested branches can be pruned out as the eggs will overwinter under the dead female’s waxy covering. 

Scale are also great attractors of the beneficial insects. If lady beetles and other predators are present, a spray may not be needed.

Ultimately, good tree health is more crucial for tree insect management than any other practice. Good tree management includes watering in times of drought, averting soil compaction, adding mulch ring to prevent weeds, and preventing physical damage by lawnmowers and string trimmers.

News Source:

Kelly Allsup, 309-663-8306

News Writer:

University of Illinois Extension

Berry wine, minus the alcohol, may offer help for those with diabetes

Published August 4, 2016

URBANA, Ill. – Blueberries, and berries in general, are among foods labeled as “diabetes superfoods” by the American Association of Diabetes. Food science researchers at the University of Illinois have found that fermenting berries may improve their antidiabetic potential even more.  

Recent research at the U of I includes the development of an alcohol-free blueberry-blackberry “wine” that those suffering from diabetes—who typically must avoid alcohol—can enjoy, while potentially reducing the effects of Type 2 diabetes.

“Unfortunately the number of people with diabetes is increasing astronomically around the world,” says Elvira de Mejia, a food chemist in the Department of Food Science and Human Nutrition at U of I. “There are 100 million people around the world who have diabetes and that is increasing, without counting the ones who may be pre-diabetic and not know it.”

Previous research has shown that dietary blueberries may play a role in reducing hyperglycemia in obese mice, therefore de Mejia and colleagues wanted to determine if a fermented, dealcoholized blueberry-blackberry beverage would enhance the potential of the phenolic compounds in the berries that are responsible for reducing diabetic markers.

A new study shows that the fermented berry beverage did reduce the development of obesity and blood glucose levels in mice on a high-fat diet.   

The researchers had already determined that the berries, when fermented at low temperatures, resulted in an improved and higher concentration of anthocyanins. Anthocyanins, found in the pigments of fruits such as blueberries, grapes, and apples, have been shown to promote insulin sensitivity, decrease blood glucose levels in the blood, and enhance insulin secretion.

“We know that fruits, vegetables, cereals, legumes, and berries are good, but here we explain that after fermentation we improve and increase the concentration of these pigments [anthocyanins] and they are very high antioxidant components that benefit the body,” de Mejia says.

A previous cell culture study with the alcohol-free blueberry-blackberry wine, showed good results toward inhibiting enzymes related to glucose absorption.

“In this in vivo study, as we increased the concentration of these anthocyanin-enriched extractions from blueberries and blackberries we saw an improvement in the uptake of glucose, meaning that the animals with the increased concentration were not as much in a state of hyperglycemia as the other animals.”

The beverage included a ratio of 70 percent fermented blackberries to 30 percent fermented blueberries. The berries were collected from varieties grown at U of I’s Dixon Springs Agricultural Research Station in southern Illinois. Alcohol was removed from the beverage by rotoevaporation and was replaced with water. Some of the sugars left over after fermentation were also removed in the process.

“We optimized the best ratio between blueberries and blackberries. Blackberries are very unique and I think that’s one of the reasons why we selected a high concentration of them in this study. Blackberries have a very specific profile of anthocyanins, and that was amazing at lowering the absorption of glucose in this case,” de Mejia says.

During the study, groups of mice with diet-induced obesity and hyperglycemia were given the fermented berry beverage or the beverage with higher or lower enriched concentrations of the anthocyanins (0.1x, 1x, or 2x). Another group was given sitagliptin, a commonly used medication for diabetes, and another group was given water only. All groups ate the same diet, calories, and amount of sugars otherwise.

While benefits were seen in all groups drinking the fermented beverage, de Mejia says the group on the highest concentration of anthocyanins (2x) showed the greatest results, comparable to what was observed in the group on sitagliptin. This included no increase in body weight, which de Mejia says was a surprise.

“That was not our objective really, we were just looking for markers of diabetes,” she says. “But it was very impressive to see.”

The researchers also observed that glucose was deposited into tissue more than absorbed by and present in the blood, as well. “You want to avoid high glucose in the blood stream, and you want uptake into muscle, liver, and organs, and to keep the level in plasma and blood normal. We saw a reduction of glucose in the blood with the beverage, even in the beverage before it was enhanced,” de Mejia says.

They also saw an effect on oxidative stress in the obese mice.  “We saw that in the animals on 2x the enriched anthocyanins, the oxidative species went down, meaning they were kind of protected against oxidation. From that stand point, it was very positive looking at the oxidative stress of the animals because that can damage protein and DNA.”

Regarding the mechanism of action in reducing the diabetic effects, de Mejia says that the antioxidant power of the anthocyanins plays a very important role. “Markers of inflammation went down too. That’s very, very, important. They are correlated. With obesity, less fat means less inflammation, and less oxidative stress. I think it is more toward that pathway of lowering oxidative stress and inflammation and lowering fat.  It was very surprising to us,” she adds.

Producing this berry wine, complete with the benefits of fermentation but without the alcohol, provides an opportunity for wine makers, de Mejia says.

“There are some bigger wineries/companies that are producing dealcoholized wine for diabetics, but from grapes. It is available in California, for example.  I think the novelty of this work is mainly the combination of the blackberries and blueberries and the concentration of anthocyanins as part of the pigment. But it is perfectly doable and I hope that companies can see that there is a market. And it’s delicious,” she adds.

While the berry wine may not be able to replace medications for diabetics, de Mejia says it could help reduce the amount of medication needed; always under the doctor’s supervision and approval.

“There needs to be more studies to see how the anthocyanins work in the presence of medication, to see if they work synergistically, for example. Then, maybe, you could decrease the amount of the drug. All of these drugs for diabetes have adverse effects after so many years of use, even the safest ones.

“We need to consider diet, exercise, lowering body weight, and all the different strategies that the American Association of Diabetes recommends, and maybe in the long run, of course with approval of a physician, you could decrease the level of the drug to keep glucose under control.”

“Alcohol-free fermented blueberry-blackberry beverage phenolic extract attenuates diet-induced obesity and blood glucose in C57BL/6J mice” is published in the Journal of Nutritional Biochemistry. Co-authors include Michelle H. Johnson, Matthew Wallig, Diego A. Luna Vital, and Elvira G de Mejia. The paper can be accessed online at http://dx.doi.org/10.1016/j.jnutbio.2015.12.013.

Planting a fall vegetable garden

Published August 4, 2016

URBANA, Ill. - Planting a vegetable garden doesn’t just happen in the spring. “Many of the vegetables that we grow in the spring can be planted in late summer or early fall,” says University of Illinois Extension horticulture educator Ken Johnson. 

“By the time summer rolls around many of our cool-season plants that were planted in the spring are past their prime,” says Johnson. “They become tough and bitter and will often bolt, like radishes and spinach. By planting these cool-season crops again, you can extend your gardening season and have fresh produce longer.” 

Johnson says there are several other advantages to planting a fall vegetable garden.

“There are often fewer pest and weed problems in the fall compared to the spring. Many vegetables have better quality when they are grown in the fall.  Some vegetables develop better flavor when grown in the fall, particularly after they have gone through a frost. Fall gardens often require less time and labor because the soil has already been worked in the spring.” 

According to Johnson, vegetables that are typically grown in a fall vegetable garden fall into the semi-hardy and hardy categories. Semi-hardy plants, such as beets, carrots, cauliflower, and lettuce can tolerate light frosts as low as 32 degrees F.  Hardy plants, such as broccoli, cabbage, radishes, and spinach can tolerate hard frosts down to 28 degrees F.  

“To determine when you should plant your vegetables, you need to determine when your first frost usually occurs,” Johnson says. “For central Illinois it is generally mid-October.  Start with that date and count backwards for the number of days it takes the crop to mature. It’s wise to add a week or two for the fall factor because temperatures are getting cooler. Development slows compared to spring when temperatures get warmer.”

Most of the vegetables grown in the fall vegetable garden, Johnson says, can be directly seeded in the garden. Some vegetables, like broccoli and cauliflower, are best done as transplants. “Unfortunately, transplants are not easy to find in the summer for these plants, so to make your own, start the seed indoors 6 to 8 weeks before you want to plant them in the garden.”

Before planting a fall garden, Johnsons says to clean it. “Remove any crop residues from previous crops and pull any weeds that may be present. Soil can also be tilled and 1 to 1 ½ pounds of an all-purpose fertilizer (per 100 square feet) or composted organic matter can be incorporated. When planting seeds, follow the directions on the seed packets. Make sure to keep the soil moist until the seeds have germinated. Because the seeds are being planted at the end of summer, the soil moisture will need to be monitored closely.”

According to Johnson, a light covering of mulch or even a board can be placed over the seeds to help retain moisture in the soil. If using a board, he says to remove it after the seeds germinate. “Checking the seed packet will give you an idea of how many days it will take for the seeds to germinate. Make sure to check under the board frequently for sprouting seeds. It’s helpful to provide some shade to seedlings in the afternoon while the temperatures are still high and the plants have yet to become well established. After your plants have become established, the maintenance is just like any other garden.  Make sure to control weeds and pests if necessary, and water when needed.”

News Source:

Ken Johnson, 217-243-7424

News Writer:

University of Illinois Extension

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