2017 Field Crop Fungicide Efficacy Tables Now Posted

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Damon Smith, Extension Field Crops Pathologist, Department of Plant Pathology, University of Wisconsin-Madison

Northern Corn Leaf Blight symptoms on a corn leaf.

The 2017 fungicide efficacy tables are now posted for foliar diseases of corn, soybeans, and small grains. New this year is an added efficacy table for fungicides effective against seedling diseases of soybean. You can access these tables by clicking directly on the links imbedded in this page or by clicking on the Fungicide Information tab above, and scrolling down the page to find the tables. The efficacy ratings are generated based on independent, University efficacy trial data from across the U.S. If you can’t find a particular product on the table, it is likely that it isn’t commonly used, or there isn’t enough data to confidently generate an efficacy rating. Remember to follow all label recommendations attached to the fungicide container. The label label is the law!

2016 Wisconsin Field Crops Pathology Fungicide Tests Summary Now Available

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Damon L. Smith, Extension Field Crops Pathologist, University of Wisconsin-Madison

The 2016 Wisconsin Field Crops Pathology Fungicide Tests Summary is now available online as a downloadable PDF. This report is a concise summary of pesticide related research trials conducted in 2016 under the direction of the Wisconsin Field Crops Pathology program in the Department of Plant Pathology at the University of Wisconsin-Madison.  We thank many summer hourlies and research interns for assisting in conducting these trials.  We would also like to thank Carol Groves, Jaime Willbur, Megan McCaghey, Bryan Jensen, John Gaska, Adam Roth and Shawn Conley for technical support.

Mention of specific products in this publication are for your convenience and do represent an endorsement or criticism.  This by no means is a complete test of all products available.  You are responsible for using pesticides according to the manufacturers current label.  Follow all label instructions when using any pesticide.  Remember the label is the law!

To download the current report, or past reports visit the SUMMARIES page by clicking here.

2016 Wisconsin Pest Management Update Tour Slides Now Live!

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Damon L. Smith, Extension Field Crops Pathologist, University of Wisconsin-Madison

Yet another Wisconsin Pest Management Update Tour is in the books. It was great to see everyone again this year. I hope you found value in the presentations and that information can improve farm productivity.  As promised, I have uploaded the slides from the 2016 tour with some of our preliminary data from 2016. You can download a PDF by CLICKING HERE. Hope to see you at a winter meeting near you!

Corn Stalk Rots and Ear Rots: A Double Whammy for Wisconsin Corn Farmers

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Damon L. Smith, Extension Field Crops Pathologist, University of Wisconsin-Madison

Figure 1. Anthracnose stalk rot symptoms in a cut corn stalk.

Figure 1. Anthracnose stalk rot symptoms in a cut corn stalk.

The 2016 growing season is going to end with many challenges for Wisconsin farmers. The excessively wet weather has slowed or ended harvest of corn silage and grain harvest has barely started in much of the state. Couple this with warm and wet weather is August and we have a double whammy of stalk rot and ear rot issues to contend with this fall.

What is the Primary Stalk Rot Issue in Wisconsin?

Anthracnose stalk rot (Fig. 1) has been a major concern for Wisconsin corn growers this season. Anthracnose stalk rot is typically worse in fields in a corn-on-corn rotation, and/or no-tilled, and planted to a susceptible hybrid. We have observed several fields with significant lodging and wind damage where anthracnose stalk rot has advanced quickly (Fig. 2). In other fields lodging has been minimal, but some anthracnose stalk rot can be found. In addition, to stalk rot anthracnose, we have also observed Fusarium stalk rot and Gibberella stalk rot. The occurrence of these stalk rots has been much less than that of anthracnose stalk rot.

Figure 2. Corn field with considerable lodging due to anthracnose stalk rot.

Figure 2. Corn field with considerable lodging due to anthracnose stalk rot.

Why did stalk rots start so early in 2016?

The late onset of northern corn leaf blight (NCLB) this season likely contributed to increased stalk rot this season. It has been documented that late season increase in leaf blight diseases, such as NCLB, can cause increased stress that leads to higher levels of stalk rot. Also, ears were large and yield potential appeared high this season. These large yield potentials may have led to increased scavenging of resources from stalks leading to more stalk stress. These stress issues, combined with excessively moist and mild conditions, likely led to the occurrence of higher levels of stalk rot in 2016.

What should I do if I have a field with stalk rot?

In fields were stalk rot is an issue, harvest as early as possible to avoid yield losses from lodging. Delaying harvest will increase the likelihood of lodging which will increase harvesting issues. Once conditions dry enough to allow combines to run, fields with higher levels of stalk rot and/or lodging should be prioritized for harvest.

What should I do about stalk rot for next season?

Management of anthracnose stalk rot (and for any of the stalk rots) is multi-faceted. First, choose hybrids with the best resistance available. Hybrids that also have good resistance to foliar diseases will also offer an advantage when managing stalk rot, as foliar disease can stress corn plants and lead to increased risk of anthracnose stalk rot. Cultural practices such as crop rotation and tillage to manage surface residue can also help. Other practices that reduce plant stress such as balanced fertilization, proper planting population, providing suitable drainage, and using well adapted hybrids for your location will reduce the risk of anthracnose stalk rot.

Fungicides are not recommended for managing anthracnose stalk rot. Attempts to use fungicides to manage anthracnose stalk rot often result in high variability and little translation to a yield advantage. In 2015 we conducted a corn fungicide trial where anthracnose stalk rot was detected at harvest. While higher levels of stalk rot were observed, and some treatments did lead to a significant reduction in stalk rot severity, no differences in lodging or yield were identified among the treatments. To view results of this 2015 trial, click here and scroll down to pages 2 and 3.

What corn ear rots and mycotoxins should I watch out for?

Figure 1. Moldy growth on a corn ear caused by the Diplodia ear rot fungus.

Figure 3. Moldy growth on a corn ear caused by the Diplodia ear rot fungus.

With all the wet weather late in the 2016 season, several ear rots have appeared in corn around much of the state. Ear rots caused by fungi in the groups Diplodia (Fig. 3), Fusarium, and Gibberella (Fig. 4) will be the most likely candidates to watch for as you begin harvest.  Fusarium and Giberrella are typically the most common fungi on corn ears in Wisconsin.  This group of fungi not only damage kernels on ears, but can also produce toxins called mycotoxins.  These toxins (fumonisins and vomitoxin) can threaten livestock that are fed contaminated grain.  Thus grain buyers actively test for mycotoxins in corn grain to monitor mycotoxin levels to be sure they are not above certain action levels established by the U.S. Food and Drug Administration (FDA).

The FDA has established maximum allowable levels of fumonisins in corn and corn products for human consumption ranging from 2-4 parts per million (ppm).  For animal feed, maximum allowable fumonisin levels range from 5 ppm for horses to 100 ppm for poultry. Vomitoxin limits are 5 ppm for cattle and chickens and 1 ppm for human consumption.

Figure 4. Symptoms and signs of Gibberella ear rot of corn.

Figure 4. Symptoms and signs of Gibberella ear rot of corn.

Diplodia ear rot (Fig. 5) is not as common in Wisconsin. However, the weather pattern this season was favorable for occurrence of this disease. This disease is often more severe in years where dry weather precedes silking, followed by wet weather immediately after silking. Diplodia ear rot does not produce mycotoxins. While this disease does not result in mycotoxin accumulation, it can cause grain yield loss and quality issues.

For more information about ear rots and to download a helpful fact sheet produced by a consortium of U.S. corn pathologists, CLICK HERE.

Figure 5. Signs and symptoms of the Diplodia ear rot fungus inside a split corn ear.

Figure 5. Signs and symptoms of the Diplodia ear rot fungus inside a split corn ear.

How do I reduce mycotoxin risks at harvest?

Before harvest, farmers should check their fields to see if moldy corn is present. Sample at least 10-20 ears in five locations of your field. Pull the husks back on those ears and observe how much visible mold is present. If 30% or more of the ears show signs of Gibberella or Fusarium ear rot then testing of harvested grain is definitely advised. If several ears show 50-100% coverage of mold testing should also be done. Observe grain during harvest and occasionally inspect ears as you go. This will also help you determine if mycotoxin testing is needed.

If substantial portions of fields appear to be contaminated with mold, it does not mean that mycotoxins are present and vice versa. Remember, Diplodia ear rot does not produce mycotoxins. However, if you are unsure, then appropriate grain samples should be collected and tested by a reputable lab.  Work with your corn agronomist or local UW Extension agent to ensure proper samples are collected and to identify a reputable lab.  If tests show high levels of mycotoxins in grain, that grain SHOULD NOT BE BLENDED with non-contaminated corn.

For more information on mycotoxins and to download a fact sheet, CLICK HERE.

Helpful information on grain sampling and testing for mycotoxins can be found by CLICKING HERE.

For a list of laboratories that can test corn grain for mycotoxins, consult Table 2-16 in UW Extension publication A3646 – Pest Management in Wisconsin Field Crops.

How should I store corn from fields with ear rots and mold?

If you observe mold in certain areas of the field during harvest, consider harvesting and storing that corn separately, as it can contaminate loads; the fungi causing the moldy appearance can grow on good corn during storage.  Harvest corn in a timely manner, as letting corn stand late into fall promotes Fusarium and Gibberella ear rots.  Avoid kernel damage during harvest, as cracks in kernels can promote fungal growth.  Also, dry corn properly as grain moisture plays a large roll in whether corn ear rot fungi continue to grow and produce mycotoxins.  For short term storage over the winter, drying grain to 15% moisture and keeping grain cool (less than 55F) will slow fungal growth.  For longer term storage and storage in warmer months, grain should be dried to 13% moisture or less. Fast, high-heat drying is preferred over low-heat drying. Some fungi can continue to grow during slow, low-heat drying. Also, keep storage facilities clean.  Finally, mycotoxins are extremely stable compounds: freezing, drying, heating, etc. do not degrade mycotoxins that have already accumulated in grain. While drying helps to stop fungal growth, any mycotoxins that have already accumulated prior to drying will remain in that grain. The addition of acids and reducing pH can reduce fungal growth but will not affect mycotoxins that have already accumulated in harvested grain.

For more information on properly storing grain and to download a fact sheet on the subject, CLICK HERE.

References

This article is a compilation of the following previously written resources:

Smith, D.L. 2016. Wisconsin Late-Season Corn Disease Update. /2016/09/07/wisconsin-late-season-corn-disease-update/.

Smith, D.L. and Mitchell, P. D. 2016. Wet Wisconsin: Moldy Corn and Crop Insurance. http://ipcm.wisc.edu/blog/2016/09/wet-wisconsin-moldy-corn-and-crop-insurance/.

Wisconsin Late-Season Corn Disease Update

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Damon L. Smith, Extension Field Crops Pathologist, University of Wisconsin-Madison

Figure 1. Anthracnose stalk rot symptoms in a cut corn stalk.

Figure 1. Anthracnose stalk rot symptoms in a cut corn stalk.

NCLB and Anthracnose Stalk Rot

As corn silage harvest has begun and the corn grain crop is finishing, there have been some disease issues of note in Wisconsin. Northern corn leaf blight (NCLB) activity has picked up quickly over the last several weeks. This is due to the fact that the weather has become much cooler and has remained wet. These conditions are favorable for the fungus. You will remember that NCLB was observed very early this season. See my previous post on this topic by clicking here.The hotter and dryer weather we saw mid-season was not only good for corn growth, but it kept the NCLB pressure minimal during the critical time of silking and pollination. As stated in the fourth edition of the “Compendium of Corn Diseases” (Carson, 2016) direct yield losses from NCLB are typically minimal if infection is moderate or delayed until 6 weeks after silking. Therefore, the expected direct yield loss from NCLB in Wisconsin in 2016 is expected to be low, due to its late onset.

Figure 2. Corn field with considerable lodging due to anthracnose stalk rot.

Figure 2. Corn field with considerable lodging due to anthracnose stalk rot.

Certainly, there are other issues to consider with this late onset of NCLB. Dry-down will be accelerated. If you have a considerable epidemic in silage corn, then it would be advisable to try to chop as quickly as possible or consider taking the crop as high-moisture corn. Another issue to consider is the fact that a late-season NCLB epidemic can increase the risk for stalk rot issues. We have observed earlier than typical onset of anthracnose stalk rot this season (Fig. 1). Anthracnose stalk rot has been observed in many fields, with a range in severity dependent on the hybrid resistance and field history. Fields in a corn-on-corn rotation, and/or no-tilled, and planted to a susceptible hybrid are at high risk of severe symptoms. We have observed several fields with significant lodging and wind damage where anthracnose stalk rot has advanced quickly (Fig. 2). In other fields lodging has been minimal, but some anthracnose stalk rot can be found.

Management of anthracnose stalk rot is multi-faceted. First, choose hybrids with best resistance available. Hybrids that also have good resistance to foliar diseases will also offer an advantage when managing stalk rot, as foliar disease can stress corn plants and lead to increased risk of anthracnose stalk rot. Cultural practices such as crop rotation and tillage to manage surface residue can also help. Other practices that reduce plant stress such as balanced fertilization, proper planting population, providing suitable drainage, and using well adapted hybrids for your location will reduce the risk of anthracnose stalk rot. Finally, in fields were stalk rot is an issue, harvest as early as possible to avoid yield losses from lodging.

Fungicides are not recommended for managing anthracnose stalk rot. Attempts to use fungicides to manage anthracnose stalk rot often result in high variability and little translation to a yield advantage. In 2015 we conducted a corn fungicide trial where anthracnose stalk rot was detected at harvest. While higher levels of stalk rot were observed, and some treatments did lead to a significant reduction in stalk rot severity, no differences in lodging or yield were identified among the treatments. To view results of this 2015 trial, click here and scroll down to pages 2 and 3.

Bacterial leaf streak – A new disease of corn in the U.S.

Bacterial leaf streak (BLS) of corn has recently been reported for the first time on corn in the U.S. The first reports were in Nebraska with subsequent reports coming in from other states in the U.S. corn belt including Iowa, Illinois, Colorado, and Kansas. Efforts are underway in Wisconsin to monitor for the disease. As of this writing, BLS has not been found in Wisconsin. However, survey and scouting efforts are continuing, to monitor for this disease.

Bacterial leaf streak is caused by a bacterium named Xanthomonas vasicola pv. vasculorum. Very little is understood about this disease on corn, as it is so new. This pathogen presents no risk to humans or animals and there is little evidence to suggest that it will have an adverse effect on corn yield and quality. You can click here to read the USDA APHIS Statement on Xanthomonas vasicola pv. vasculorum. To learn more about the disease and to watch a video by Dr. Tamra Jackson-Ziems at the University of Nebraska CLICK HERE. Helpful information and hints on initially diagnosing BLS can be found HERE.

If you suspect that you have BLS in your corn crop in Wisconsin, leaf samples of corn plants can be sent in a sealed plastic bag with NO added moisture to the University of Wisconsin Plant Disease Diagnostic Clinic (PDDC). Information about the clinic and how to send samples can be found by CLICKING HERE.

References

Esker, P. 2016. Anthracnose stalk rot: in “Farmers Guide to Corn Diseases” Edited by: K. Wise, D. Mueller, A. Sisson, D. Smith, C. Bradley, and A. Robertson. APS PRESS.

M.L. Carson. 2016. Northern Corn Leaf Blight: in “Compendium of Corn Diseases, Fourth Edition.” Edited by: G.P. Munkvold and D.G. White. APS PRESS.

 

Wisconsin Corn Southern Rust Update – August 26, 2016

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Damon L. Smith, Extension Field Crops Pathologist, University of Wisconsin-Madison

Corn Southern Rust positive confirmation map, by state county

Corn Southern Rust positive confirmation map, by state county

Southern rust of corn has been confirmed for the first time this season by the UW Plant Disease Diagnostic Clinic (PDDC) in Wisconsin. The positive sample was submitted from Rock Co. along the Wisconsin/Illinois state line and confirmed on August 25, 2016. As previously predicted, southern rust did make it to Wisconsin this year, however, its arrival is late enough that it should have minimal impact on yield. We published an article on WisContext about some reasons why this occurrence was expected in 2016, you can click here to learn more.

Most corn in Wisconsin is at least well into the milk stage (R3) or dough (R4). Once corn reaches the milk stage (R3), risk of yield loss from this and other foliar pathogens begins to quickly decline. Thus spraying fungicide at this time of the season is not recommended. If you would like to learn more about telling the difference between the two types of rusts that occur on corn, or management of southern rust specifically, see my previous article by CLICKING HERE.

If you need assistance in identifying rust on corn, leaf samples of corn plants can be sent in a sealed plastic bag with NO added moisture to the University of Wisconsin Plant Disease Diagnostic Clinic (PDDC). Information about the clinic and how to send samples can be found by CLICKING HERE.

Wisconsin Corn Southern Rust Update – August 10, 2016

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Figure 1. Corn Southern Rust Map - August 10, 2016

Figure 1. Corn Southern Rust Map – August 10, 2016

Damon Smith, Extension Field Crops Pathologist, University of Wisconsin-Madison

Wisconsin corn continues to remain free of southern rust as of August 10, 2016. However, new confirmations have been reported in southern Indiana (Fig. 1). You should continue to scout the corn crop for southern rust. However, the window of risk is quickly passing for much of Wisconsin. Once corn reaches the milk stage (R3), risk of yield loss from this and other foliar pathogens begins to quickly decline. Thus, as long as corn remains free of southern rust for another week or so, we will be in good shape for the rest of the season. If you need assistance in identifying rust on corn, leaf samples of corn plants can be sent in a sealed plastic bag with NO added moisture to the University of Wisconsin Plant Disease Diagnostic Clinic (PDDC). Information about the clinic and how to send samples can be found by CLICKING HERE.

Wisconsin Corn Disease Update – July 27, 2016

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Damon Smith, Extension Field Crops Pathologist, University of Wisconsin-Madison

Northern Corn Leaf Blight

Over the last week concerns have been increasing over corn diseases as we are at the critical time to make fungicide application decisions. See my previous post about the early onset of northern corn leaf blight (NCLB) in Wisconsin in 2016 by CLICKING HERE. While NCLB can be observed in many corn fields in the state, it can be difficult to find. The hot weather this year has managed to keep that disease in check. While now is a good time to scout and make spray decisions, remember that it would take 50% or more of plants in the field with 10% or more of the ear leaves covered with lesions of NCLB prior to the milk growth stage before significant yield loss will occur.

Goss’s Wilt

Just this week, the University of Wisconsin-Madison Plant Disease Diagnostic Clinic (PDDC) positively confirmed the first Goss’s wilt sample of 2016. This sample came from Grant Co. Other samples have arrived, but no definitive confirmation has been made in other counties in the state. For information on Goss’s Wilt you can visit my previous posting from 2015 by CLICKING HERE.

Rusts

Figure 1. 2016 Southern Rust Advancement in The U.S. as of July 27. Red highlights indicate counties where southern rust has been confirmed.

Figure 1. 2016 Southern Rust Advancement in The U.S. as of July 27. Red highlights indicate counties where southern rust has been confirmed.

Southern rust continues to be a disease to scout for in Wisconsin. No positive confirmations have been made in Iowa, Illinois, or Wisconsin. However, the disease has been confirmed in parts of Nebraska (Fig. 1). We have scouted several fields of dent corn and also sweet corn. Only pustules of common rust have been observed in these fields. Conditions have been suitable for this disease over the last several weeks. Remember that rust pathogens have to be blown in from the south. The inoculum of the fungi that cause these diseases do not overwinter in Wisconsin. To learn more about the two types of rust that can affect corn in Wisconsin and how to manage them, CLICK HERE to visit my post from last week.

Remember to get out there and SCOUT, SCOUT, SCOUT!

Corn Rusts in Wisconsin

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Damon L. Smith, Extension Field Crops Pathologist, University of Wisconsin-Madison

Figure 1. Brick-red Pustules of the common rust fungus on a corn leaf.

Figure 1. Brick-red Pustules of the common rust fungus on a corn leaf.

I have been receiving lots of questions over the last couple of weeks about rusts in corn. Folks are identifying pustules of common rust on field and silage corn in Wisconsin. Common rust is caused by the fungus Puccinia sorghi. Symptoms can include chlorotic flecks that eventually rise and break through the epidermis to produce pustules of brick-red spores (Fig. 1). Typically these pustules are sparsely clustered on the leaf. They can also appear on other parts of the plant including the husks and stalks. Conditions that favor the development of common rust are periods of high humidity and nighttime temperatures that remain around 70F with moderate daytime temperatures. This fungus needs very little free moisture for infection to occur. Thus, the weather conditions in Wisconsin over the last month have been somewhat conducive for this disease. However, very hot and dry weather can slow or stop disease development.

Management of Common Rust

Management for common rust primarily focuses on resistant hybrids. Most modern commercial hybrids have excellent resistance to common rust. Remember resistance is not immunity, so some pustule development can be observed even on the most resistant hybrids. Some inbred corn lines and specialty corn can be highly susceptible to common rust. Under these circumstances a fungicide may be necessary to control common rust. Fungicides with efficacy toward common rust can be found on the Corn Fungicide Efficacy Table. Most of the hybrids I have scouted this season have some pustules, however incidence and severity is relatively low. Therefore, a fungicide application to control common rust isn’t needed for most of these hybrids in Wisconsin. Residue management or rotation is typically not needed for this disease as inoculum (spores) have to be blown up on weather systems from the southern U.S.

Figure 2. Southern rust pustules on a corn leaf. Photo credit: Department of Plant Pathology., North Carolina State University, Bugwood.org

Figure 2. Southern rust pustules on a corn leaf. Photo credit: Department of Plant Pathology., North Carolina State University, Bugwood.org

A related rust that we need to pay close attention to this season is southern rust. Southern rust is caused by the fungus Puccinia polysora. Symptoms of southern rust are different from common rust in that they are typically smaller in size and are often a brighter orange color (Fig. 2). Pustules of southern rust also typically only develop on the upper surface and will be be more densely clustered. Favorable conditions for southern rust development are similar to those for common rust. high humidity and temperatures around 80F encourage disease development. However, very little free moisture is need for infection to occur. Southern rust is typically a rare occurrence in Wisconsin. When it does occur, it is usually in the southern and southern western portions of the state, with epidemics initiating late in the season. Spores of this fungus have to be blown up from tropical regions or from symptomatic fields in the southern U.S. The fungus can not overwinter in Wisconsin. While southern rust epidemics can be rare events in Wisconsin, the disease can be serious when it occurs. Therefore close monitoring of forecasts and scouting are needed to make timely in-seaosn management decision.

Figure 3. Corn Southern Rust Observations as of July 22, 2016

Figure 3. Corn Southern Rust Observations as of July 22, 2016

Currently the Corn Southern Rust iPIPE map is showing numerous confirmed cases of southern rust in the southern, southeastern U.S. and Kansas and Kentucky. No confirmed cases have been identified in Illinois, Iowa or Wisconsin. However, close attention should be paid to this disease in 2016 as the confirmed cases this year have been earlier than in the past. This could mean that conditions are ripe for movement of southern rust inoculum into Wisconsin.

Management of Southern Rust

Traditionally resistance was used to manage southern rust. However, in 2008 a resistance-breaking race of the southern rust fungus was confirmed in Georgia. Thus most modern hybrids are considered susceptible to southern rust. Rotation and residue management have no effect on the occurrence of southern rust. The southern rust fungus has to have living corn tissue in order to survive and can not overwinter in Wisconsin. Fungicides are typically used to control southern rust in parts of the U.S. where this is a consistent problem. Efficacy ratings are also available for fungicides against southern rust on the Corn Fungicide Efficacy Table. Should southern rust make its way to Wisconsin prior to the “milk” (R3) growth stage in corn, it could cause yield reductions. Growers and consultants should scout carefully through the R3 growth stage and be sure to properly identify the type of rust observed. If you need assistance in identifying rust on corn, leaf samples of corn plants can be sent in a sealed plastic bag with NO added moisture to the University of Wisconsin Plant Disease Diagnostic Clinic (PDDC). Information about the clinic and how to send samples can be found by CLICKING HERE.

Other Useful Resources about Rusts on Corn

Purdue Extension Fact Sheet – Common and Southern Rusts of Corn

2014 Crop Alert – University of Nebraska

Video by Dr. Tamra Jackson-Ziems of the University of Nebraska – Identifying Rust Diseases of Corn

Wisconsin Northern Corn Leaf Blight Update – June 29, 2016

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Damon L. Smith, Extension Field Crops Pathologist, University of Wisconsin-Madison

Since the first 2016 confirmation of northern corn leaf blight (NCLB) in Wisconsin on June 16, we have received additional corn samples from other areas of the state in my laboratory and also in the University of Wisconsin Plant Disease Diagnostic Clinic. All confirmations have been made in the laboratory, confirming the presence of the pathogen. Figure 1 shows counties, highlighted in red, where corn samples originated and were confirmed with NCLB.

While it is unusually early to find NCLB at this incidence level in Wisconsin, I continue to urge you to remain patient. All samples that we have examined have had low severity (very few and/or small lesions present on a single leaf). In addition, most of the damage has been confirmed on lower leaves which do not contribute as much to yield as the ear leaves eventually will. As I mentioned in my previous post on June 16, Our economic analyses indicate that the likelihood of positive return on investment from a fungicide will be higher when the application is made as close to the tasseling period as possible. Considering that the weather this week is very dry and severity of NCLB has been relatively low, I would encourage growers to wait until closer to tasseling before making the decision to apply fungicide. If weather over the next week or two begins to turn continually wet, then this decision should be re-evaluated at that time. To learn more about NCLB and return on investment when using fungicide CLICK HERE. To watch a video about corn diseases in Wisconsin and fungicide use in corn, CLICK HERE. Remember to continue to SCOUT, SCOUT, SCOUT!