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Downy mildew spotted in Illinois pumpkin field

Published July 31, 2015
Downy mildew on the upper surface of a pumpkin leaf in early stage. Photo courtesy of Mohammad Babadoost.

URBANA, Ill. – Downy mildew of cucurbits is a destructive disease of cucurbits, including pumpkins. According to a University of Illinois vegetable and fruit pathologist, infection in a pumpkin field has shown up in Illinois.  

Mohammad Babadoost explained that downy mildew of cucurbits was recently diagnosed by colleague Daniel Egel in a watermelon field in Lawrence County, Ill., on July 23. “I was hoping that the disease would not spread to other parts of the state. But yesterday (July 30), we observed severe infection by downy mildew pathogen in a processing pumpkin field in Mason County, Ill.,” Babadoost said. “The pathogen will likely spread to other parts of the state.”

Downy mildew of cucurbits, caused by Pseudoperonospora cubensis, is a very destructive disease of cucurbits. “The present strain of the pathogen will likely infect all cucurbit crops, including cucumber, gourd, muskmelon, pumpkin, squash, and watermelon,” Babadoost said.  “Weather conditions in Illinois are very conducive for development of downy mildew.”

Downy mildew affects leaves only. Symptoms of downy mildew vary with the host and the environmental conditions. Babadoost explained that the first symptom is usually the appearance of indistinct pale green areas on the upper leaf surface. The pale green areas soon become yellow in color and angular to irregular in shape, bounded by the leaf veins.

“As the disease progresses, the lesions may remain yellow or become brown and necrotic. During moist weather, the corresponding lower leaf surface is covered with a downy, pale gray to purple mildew. Often an upward leaf curling will occur,” he added.

If you don’t have the disease in your field yet, Babadoost recommends including chlorothalonil (e.g., Bravo Weather Stik) in weekly sprays. If downy mildew is observed in the field, spray cucurbit crops with one the following fungicide combinations at weekly intervals: Revus 2.09SC or Previcur Flex 6SC or Tanus 50WG or Ranman 3.6SC or Gavel 75DF or Zampro 525F plus chlorothalonil. 

For additional information, contact Babadoost at babadoos@illinois.edu or 217-333-1523.

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Symptoms of sudden death syndrome begin to appear in soybeans

Published July 29, 2015
Foliar symptoms of sudden death. Photo by Angie Peltier.

URBANA, Ill. - Last week, symptoms of sudden death syndrome (SDS) began to appear in April 15-planted soybeans at the University of Illinois’s Northwestern Research Center in Warren County, according to a U of I Extension educator.

Angie Peltier explained that weather during the 2015 growing season has been favorable for the development of SDS: cool, moist soils after planting followed by frequent rains. Symptoms began appearing approximately 3 weeks earlier than in 2014, she said.

Although the fungus that causes SDS (Fusarium virguliforme) infects roots of soybean seedlings very early in the growing season, foliar symptoms don’t typically appear until after soybean plants reach reproductive growth stages. Peltier said foliar symptoms begin with a yellowing of the tissue between leaf veins. This tissue then dies, becoming brown in color with only the leaf veins remaining green. Leaves eventually fall off, while petioles remain attached to the main stem. The earlier that symptoms develop and leaf drop occurs, the greater the potential for yield loss.

“Although foliar symptoms of SDS can be easily confused with those of another disease—brown stem rot—one need only split the plant lengthwise to distinguish the two,” Peltier explained. “Brown stem rot causes browning of the innermost stem tissue (pith). Stems of plants with SDS remain healthy. Blueish-white spores of Fusarium virguliforme can sometimes (not always) be seen on the roots of symptomatic plants.”

Although the most conspicuous symptoms of SDS occur in leaves, the fungus itself remains in the roots and in the stem nearest to the soil line. Foliar symptoms are caused by toxins produced by the pathogen. These toxins are carried along with water to leaves through the xylem tissue.

“The SDS disease cycle has important implications as far as management is concerned. Infection and colonization have long since taken place and there are no mid-season management tools with which to manage this disease,” Peltier said. “Management decisions must be made before the growing season begins.”

Peltier explained that the best way to manage SDS is to plant the most resistant varieties. “Soybean varieties vary considerably in their level of genetic resistance.” she said.

To provide impartial SDS resistance ratings to help soybean producers more easily compare varietal resistance among seed brands, teams led by Jason Bond of Southern Illinois University and Silvia Cianzio of Iowa State University evaluated more than 500 soybean varieties (MGs 0 to V) from 19 different seed companies. Results from these 2014 check-off sponsored trials are available online. Results from the 2015 trials will be compiled and released in October in time for producers to use when making their 2016 seed purchases.

Research has also shown that SDS may be more severe in fields that also have high populations of soybean cyst nematodes (SCN). Monitoring SCN populations and planting SCN-resistant soybean varieties can also be important components to managing SDS.

Peltier pointed out that the newest tools available for managing this disease are fungicidal seed treatments labeled specifically for SDS. Former U of I Extension plant pathologist, Carl Bradley, and his team conducted several SDS seed treatment trials. In these trials, the active ingredient in ILeVO (fluopyram) showed efficacy against SDS. Other SDS seed treatments on the market are also being evaluated, she added.

“As the season progresses and we near harvest, check out the Northwestern Illinois Research Center’s website and blog for data from our 2015 SDS seed treatment trial and other research trials at this location,” Peltier said.

New pig model will provide insights into early detection, new treatments of cancers

Published July 29, 2015

URBANA, Ill. – With many types of cancers, early detection offers the best hope for survival. However, research into new early-detection screenings, as well as possible interventional radiology and surgical treatments, has been hindered by the lack of a large animal model that would accurately reflect the types of cancers seen in human cells.

For the last several years, researchers at the University of Illinois interested in improving screening programs for cancer have studied gene expression in mice, humans, and pigs in an effort to create a large-animal model that is more relevant to human cancers.

A new study from U of I researchers and other collaborators, recently published in PLOS One, reports the creation of such a model—a genetically engineered pig that allows researchers to induce the development of the same types of tumors seen in humans, reflecting the gene pathways and gene mutations most often observed in human cancer. Due to the genetic engineering, the tumors can be induced at any tissue site at any given time.

Lawrence Schook, a geneticist in the U of I Department of Animal Sciences, said that the “oncopig” model holds great promise not only in understanding and detecting cancer earlier, but also in developing new treatments and possible cures.

“We already knew which mutations cause cancer, but we wanted a model that would allow us to look for early detection of cancers,” Schook said. “Currently, if a patient is diagnosed with stage 3 or 4 of certain types of cancer, it is often too late for drug, radiation, or surgical interventions. If we could induce tumors in various tissues at very specific times, we could come up with early diagnoses and screening tools. That will allow us, if you have early onset cancer, to do something early on in the progression of the cancer. That’s been our goal.”

Schook said the researchers are especially targeting cancers that are more difficult to diagnose in their early stages, including pancreatic, liver, lung, and bladder cancers. “These are devastating diseases for which early detection is critical. If we could detect them earlier, we have ways to treat them,” he said.

During a decade-long collaboration with Professor Christopher Counter at Duke University, Schook said researchers identified the pig as a better model than mice because of the pig’s similarities in anatomy, size, metabolism, and genetics to humans. And although the mice in their previous studies did develop tumors, the tumors were not similar to the tumors clinically observed in humans. And treatments, such as radiation or surgery, are simply not scalable to mice.

“Many people who are diagnosed with liver, pancreatic, or lung cancer, for example, have either been smokers or drinkers, or are overweight, or have cardiovascular disease. These are comorbidities. With the pig model, we can induce comorbidities in pigs. We can induce tumors in tissue that would be very similar to clinical human tumors,” Schook said.

In the researchers’ first paper, they described isolating fibroblasts from pigs, inserting the genes with the mutations into these cells, and testing for tumor formation in the donor pig’s ear. “We know that those mutations cause tumors in humans, so we asked if we would see that in pigs and the answer was yes. It was the same pathway, the same genes, and the same mutation,” he said.

Schook explained that because mutations in the genes (KRAS or TP53) are seen in nearly 50 percent of all human cancer, they targeted those genes in the pig model. The researchers engineered a construct of the pig genes with the added mutations. Because this construct is not expressed in normal cells, they “activated” expression of the mutated genes with an injection of a Cre recombinase enzyme, which induces tumors by signaling the gene to recombine.

“The pigs that are born with this gene inserted in them are normal animals, and if we expose a particular cell to this Cre enzyme, it gets activated and becomes tumorigenic. We can have control over the cell, as well as the location and the timing of inducing this signal,” Schook explained. “We can target individual cells or tissues.”

Depending on the location of injection, Schook said different types of tumors developed in the model. “It was what we expected. It was a proof of concept,” he noted.

Because of the ability to target individual locations, the model is applicable to a range of types of cancers. “It also allows us to develop approaches to treating different cancers, depending on where they are located in the body,” Schook explained. “We can begin to look at location and interventional radiology and microsurgery.”

Along with strong the collaboration with Counter at Duke University, Schook said the University of Missouri’s National Swine Resource and Research Center (NSRRC), supported by the National Institutes of Health (NIH), contributed to the project.

“We’re excited that this pig is a national and international model that will be available to anybody doing research. They can get the model through the NSRRC,” he said.

Schook and Laurie Rund, a research assistant professor in animal sciences, have also collaborated for several years with Champaign-Urbana-based Acoustic MedSystems, a medical device research and development company, in evaluating new image-guided minimally invasive ablative surgical methods. 

“Currently, all the minimal invasive devices in the clinic or currently under investigation have never been tested in human-scale large-animal tumor models. All device testing has used normal tissues,” Schook said. “This model essentially offers the opportunity to evaluate new therapies and devices in a human-size animal model.”

Because of the “oncopig” model, Acoustic MedSystems (AMS) has developed several image-guided minimally invasive devices for treatment of tumors in several sites, including liver, kidney, spine, prostate, and brain. Recently, U of I and AMS piloted the use of the oncogenic pig model for evaluating a new high-intensity ultrasound therapy system for soft tissue tumors, culminating in the submission of a research proposal to the National Cancer Institute that proposes to induce tumor growth in genetically engineered oncogenic pigs and assess the treatment efficacy of 3D spatially registered image-guided catheter-based ultrasound thermal surgery. The project will be a collaborative partnership grant between AMS and U of I, with principal investigators Schook, Rund, and Everette C. Burdette of AMS.

“Success of the proposed work using the new tumor model in a large animal that is comparable in both scale and physiology to human patients will be beneficial to validate many minimally invasive modalities in addition to ultrasound therapy, but also other energy-based modalities including cryo-ablation, radiofrequency and microwave thermal therapy,” the researchers reported in the proposal. “The validation test results from the model will ensure greater safety and permit treatment response evaluation prior to first-in-human clinical studies.”

“A genetic porcine model of cancer” was recently published in PLOS One. Co-authors include Lawrence B. Schook , Tiago V. Collares, Wenping Hu, Ying Liang, Fernanda M. Rodrigues, Laurie A. Rund, Kyle M. Schachtschneider, Fabiana K. Seixas, Kuldeep Singh, Kevin D. Wells, Eric M. Walters, Randall S. Prather, and Christopher M. Counter.

Chill-tolerant hybrid sugarcane also grows at lower temperatures, team finds

Published July 28, 2015
Postdoctoral researcher Katarzyna Glowacka, left, crop sciences professor Erik Sacks, visiting scholar Shailendra Sharma. Photo by L. Brian Stauffer.

URBANA, Ill. — U.S. farmers have long hoped to extend sugarcane’s growing range northward from the Gulf coast, substantially increasing the land available for sugar and biofuels. Several hybrid canes developed in the 1980s have proved hardy in cooler climes, surviving overwinter as far north as Booneville, Arkansas. But until now, no one had tested whether these “miscanes,” as they are called, actually photosynthesize, and thus continue to grow, when the thermometer dips.

Researchers now report that two miscanes – the offspring of crosses between sugarcane and a hardy, cold-tolerant grass, Miscanthus – perform as well as the grass species Miscanthus x giganteus at 10 degrees Celsius (50 F), staying green and converting carbon dioxide to plant matter at a steady rate. Although the rate of photosynthesis drops in the miscanes at 10 C, it doesn’t stall out altogether, as it does in sugarcane.

The researchers report their findings in the journal Global Change Biology Bioenergy.

“There are two different aspects of cold tolerance,” said University of Illinois crop sciences professor Erik Sacks, who led the research with postdoctoral researcher Katarzyna Glowacka. “Surviving over the winter is one thing, but we also need the plants to be productive at the beginning of the season and at the end of the season in a more northern – or higher altitude – environment where it’s colder, because the season is shorter as you go further north.”

Unlike tropical sugarcane, Miscanthus x giganteus is just as productive in the cool spring and autumn as in the heat of summer. It sprouts earlier than corn in the spring, and its leaves stay green and active well into the autumn.

“Typically, with sugarcane, when you lower the temperature to 10 or even 14 degrees (Celsius), there is very little growth or no growth, and leaves lose their ability to conduct photosynthesis,” Glowacka said. “The plants will not die, but they don’t grow.”

Modeling studies suggest that extending sugarcane’s growing season by 30 days – allowing it to photosynthesize in cooler temperatures the way Miscanthus does – can boost sugarcane yield by as much as 25 percent in the U.S., Glowacka said.

The researchers exposed the miscanes to 10 days of 10-degree C conditions in the laboratory, measuring the rate of photosynthesis all the while. When they raised temperatures again to 25 degrees (77 degrees F), photosynthesis rebounded in the miscanes similar to Miscanthus x giganteus. This means that the gains in chill-tolerance did not blunt sugarcane’s productivity – a happy finding, the researchers said.

Field studies confirmed the laboratory findings.

“If we could get these plants to grow as far north as hardiness zone 8, that would be really great,” Sacks said. “That’s a huge amount of land, and some of it is not very productive currently.”

The miscanes could be grown for sugar or as a productive biofuels crop on the least productive land in the American South, Sacks said.

“To avoid potential food vs. fuel concerns, we wouldn't put it in a place with highly productive agriculture, like the Mississippi Delta,” he said.

Many years of work remain before chill-tolerant miscanes are available for production on a large scale, the researchers said. But the new findings establish that sugarcane can be made chill-tolerant without losses in productivity, they said.

Co-authors Sacks, Glowacka, crop sciences professor Stephen Long and visiting scholar Shailendra Sharma are affiliates of the Carl R. Woese Institute for Genomic Biology at the U of I.

This research is part of the PETROSS (Plants Engineered to Replace Oil with Sugarcane and Sweet Sorghum) project, which is funded through the Department of Energy Advanced Research Projects Agency-Energy (ARPA-E). Collaborators on the study included scientists from the U.S. Department of Agriculture – Agricultural Research Service in Canal Point, Florida.

The paper, “Can chilling tolerance of C4 photosynthesis in Miscanthus be transferred to sugarcane?” is available online.

News Source:

Erik Sacks, 217-333-9327

News Writer:

Diana Yates, 217-333-5802

I-STEM Evaluators Serve as “Critical Friends” for STEM Education Programs

Published July 27, 2015

A trait most human beings share is that we love to receive praise about something we’re doing right, but sometimes take umbrage when we receive even constructive criticism. And folks involved with STEM education programs are no different. But when it comes to the evaluation of these programs, I-STEM evaluators work hard at being objective, describing themselves as “critical friends.” While they are pleased to inform those involved in the programs about the things they’re doing right—similar to the proverb that begins, “Better are the wounds of a friend”—they’re also willing to tell them about things that need improvement and how they could do that.  Reed entire article at http://www.istem.illinois.edu/news/istem.evaluation.html

 

Corn prices fade as supplies expected to remain in surplus

Published July 27, 2015

URBANA, Ill. – Corn futures prices increased about 90 cents per bushel from mid-June to mid-July. According to University of Illinois agricultural economist Darrel Good, the increase was driven by a combination of a smaller-than-expected USDA estimate of June 1 stocks and production concerns stemming from record June rainfall in much of the eastern Corn Belt.

“Over the past two weeks, corn futures prices have declined nearly 65 cents per bushel as production concerns have subsided,” Good said. “Expectations are for corn supplies to remain in surplus during the 2015-16 marketing year. Prices will remain at the current low level unless there is some evidence that the supply and demand balance is potentially much tighter than currently expected. 

“A slightly tighter supply and demand balance for the 2015-16 corn marketing year could be generated by a smaller carryover of old-crop corn than currently projected,” he added. “Based on the current pace of ethanol production, for example, the use of corn for ethanol production during the current marketing year (ending August 31) could be about 10 million bushels more than the current USDA projection of 5.2 billion bushels. Similarly, exports could be slightly larger than the projection of 1.85 billion bushels if Census Bureau export estimates for June, July, and August exceed the USDA export inspection estimates as was the case in the first nine months of the marketing year. However, for carryover stocks to be lower than the current projection of 1.79 billion bushels by enough to meaningfully alter the 2015-16 supply and demand balance would require larger-than-expected feed and residual use of corn during the final quarter of the marketing year.”

The USDA’s projection of 5.3 billion bushels of feed and residual use for the year implies fourth-quarter use of 522 million bushels. “That’s 111 million bushels more than the use of a year ago and the largest fourth quarter use since 2009,” Good said. “Use is expected to exceed that of a year ago due to an increase in pork and broiler production and small increases in the number of dairy cows and the number of beef cattle on feed. The number of layers has been sharply reduced due to bird flu. Fourth quarter feed and residual use will be revealed with the estimate of September 1 stocks of old crop corn to be released on September 30 and a surprise is always possible.”

 

Good said that a tighter supply and demand balance could also result from larger-than-expected consumption during the year ahead. Such a development would take time to unfold, but the opportunities for consumption to exceed the current projection appear to be limited. The USDA currently projects 2015-16 marketing-year exports at 1.875 billion bushels, 25 million more than projected for the current year. However, interest in U.S. corn is currently limited by abundant supplies of low-priced South American corn.

As of July 16, the USDA reported that only 152 million bushels of U.S. corn had been sold for export during the upcoming marketing year. On the same date last year, outstanding sales of new-crop corn totaled 232 million bushels.

“Corn used for ethanol production is projected to increase by 25 million bushels during the upcoming marketing year,” Good said. “The expected increase in ethanol production and corn consumption reflects expectations for growth in domestic gasoline consumption. Growth beyond that, however, will be limited by the 10 percent ethanol blend wall and the very slow pace of growth in the consumption of higher ethanol blends. In addition, ethanol exports are already large so that growth potential is likely limited,” he said.

The USDA projects feed and residual use of corn to decline by 25 million bushels during the year ahead. Good said that consumption should be supported at a relatively high level due to larger livestock inventories. However, hog producers have indicated that they will reduce the number of sows farrowed during the last half of 2015 and growth in the other animal sectors will likely be very modest.

“The most obvious opportunity for a tighter corn supply and demand corn balance during the year ahead  would come from a smaller-than-expected harvest,” Good said. “The USDA’s Crop Production report to be released on August 12 will contain the first survey-based yield and production forecasts for the 2015 crop. Expectations for the U.S. average yield projection are in a wide range, but have generally increased over the past two weeks as weather conditions have become less stressful and as crop condition ratings have stabilized at a high level. The average yield expectation appears to be near 165 bushels, 1.8 bushels less than projected in the July 10 World Agricultural Supply and Demand Estimates (WASDE) report .

“The August production forecast will also reflect the estimate of harvested acreage, but a large change from the June acreage forecast is not expected. Based on the projection of 81.1 million acres harvested for grain, a yield of 165 bushels would result in a crop of 13.38 billion bushels, about 150 million bushels less than projected in the July WASDE report. Still, if 2015-16 marketing-year consumption is near the current USDA projection of 13.735 billion bushels, year-ending stocks would be abundant at about 1.45 billion bushels. On the other hand, a yield forecast of 161 bushels or less would likely be sufficient to push prices back to the mid-July highs.” 

Good concluded that recent corn-price declines indicate that the market is removing the production risk premium from the price structure in anticipation of another year of surplus. The question is whether that removal is premature.

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