The Cornell Small Grains Breeding Program has announced the release of LakeEffect, the first winter malting barley released by the program in its 118-year history.
“We’re excited about LakeEffect because it couples the agronomic performance farmers want with the superior malting qualities brewers and distillers are looking for,” said Mark Sorrells, professor in Cornell’s School of Integrative Plant Science (SIPS), who led the breeding effort.
“What’s truly remarkable is that we took this from first cross to commercial release in just seven years – which is incredibly fast to move a new variety to market,” he added.
Certified seed growers are expected to harvest seed crops for commercial growers in summer 2026 for fall 2026 planting. For more information on seed availability, contact the New York Seed Improvement Program at (607) 255-9869 or nysip@cornell.edu.
The presence of the corn stunt spiroplasma was confirmed in corn fields in four non-contiguous New York Counties (Erie, Jefferson, Monroe, and Yates) in October 2024. The causal agent of corn stunt, Spiroplasma kunkelii, belongs to a specialized class of bacteria known as mollicutes which also includes phytoplasmas. Spiroplasma cells lack walls, and they have a short, spiral shape. They live an obligate lifestyle, i.e., they survive and reproduce only in living leafhopper hosts and in the phloem sieve elements of specific plant hosts. The pathogen that causes corn stunt is transmitted by the corn leafhopper, Dalbulus maidis, also not documented previously in New York (Figure 1). That status changed this October as individuals of D. maidis were caught on a yellow sticky trap in Jefferson County. One captured leafhopper was confirmed by molecular tests to be infected by S. kunkelii. This is the first documentation of the corn leafhopper and of S. kunkelii in both corn leaves and corn leafhoppers in New York.
Figure 1. Corn leafhopper, Dalbulus maidis, the insect vector of corn stunt spiroplasma, is characterized by two prominent dark dots between its eyes and a deeply imbedded V-pattern on its upper thorax. Photo courtesy of Dr. Ashleigh Faris, Oklahoma State University.
How is the spiroplasma transmitted and spread?
The corn leafhopper, D. maidis, can acquire spiroplasma through its probing mouthparts in less than an hour of feeding in phloem tissues of infected corn plants, but it can take up to two weeks of spiroplasma replication in the leafhopper’s body before the insect can then transmit the spiroplasma into the phloem of healthy corn plants. Symptoms don’t generally appear until about a month after plants have been infected. The most severe symptoms are the result of infection at early corn growth stages (from VE to V8). An infected leafhopper can transmit spiroplasma to many nearby plants and can also be blown by air currents and deposited into distant corn fields.
Where did the leafhopper and spiroplasma in New York come from?
Corn stunt is a disease complex first described nearly 80 years ago in the Rio Grande Valley of Texas. Spiroplasma kunkelii is the principal pathogen causing corn stunt. However, other pathogens, either alone or in combination, also can cause corn stunt; these pathogens include the maize bushy stunt phytoplasma, the maize rayado fino virus, and the maize striate mosaic virus. Leaf samples from New York have been archived for later testing for these additional pathogens. Over past decades, there have been observations of corn stunt symptoms in several southern and eastern states but epidemics of corn stunt with well documented isolation of S. kunkelii have been primarily in Texas, Florida, and California. In recent years, corn stunt has occurred as a yield-reducing disease primarily in Mexico, Central and South America, particularly in Argentina and Brazil. The principal vector, the corn leafhopper, can be transported long distances by air currents and carries the pathogen within it. While there is no direct proof, it is very likely that long-distance atmospheric transport of the corn leafhopper into the Midwest and Northeast in 2024 was aided by storm systems that moved north from southern states.
What are the symptoms of corn stunt?
Corn stunt symptoms present similarly to other stresses in corn, including drought, soil compaction, and phosphorous deficiency. Leaf blades and sheathes can show white or yellow stripes (loss of chlorophyl) or red or purple streaks (anthocyanin pigments) and plants may show premature senescence (but without stalk rot) (Figure 2). Corn stunt varies from several common stressors in that plants can show significant stunting and ear abnormalities such as poorly filled ears, no ears or multiple ears at the same node. Symptoms may appear in patches within a field or across larger portions of a field.
Figure 2. Corn plants testing positive for corn stunt spiroplasma showed stunting, leaf reddening, and abnormal ears in (A) Erie County and (B) Jefferson County, New York near the end of the 2024 growing season.
How was corn stunt detected in New York?
From conference calls with my field crop pathology counterparts in southern and corn belt states this summer, I became aware that, in association with stunted and discolored corn plants, corn stunt and corn leafhopper were being observed further north of their usual ranges in 2024. Yet, I thought that New York was at a sufficiently northern latitude to avoid these problems. I credit a very observant agronomy specialist, Rafaela Aguiar with Kreher Family Farms, for noticing unusual symptoms in field corn in Erie County in late summer. Rafaela, a native of Brazil and with previous agronomic experience in South America, thought the symptoms resembled corn stunt which she had seen in South America. Though I was skeptical, it turned out that Rafaela was correct. We initially collected samples of symptomatic plants (Figure 2A) from three Erie County fields and sent them to the Diagnostic Lab at Oklahoma State University. Two of the three fields came back as strongly positive for the corn stunt spiroplasma. In a race against corn harvest and frost, samples were then collected from corn in other counties where similar symptoms had been reported. Samples from Jefferson, Monroe, and Yates Counties were also positive (Figure 2B). I suggest that, given more time for scouting in October, corn stunt may have been diagnosed in many more corn fields in New York this year.
What does this mean for future corn production in New York?
Documentation of the pathogen and its insect vector in New York in 2024 demonstrated that corn stunt could occur in New York in future growing seasons. And if spiroplasma-infected corn leafhoppers arrive at earlier corn growth stages, significant yield losses could result. Then again, the atmospheric pathways that carried corn leafhoppers to New York in 2024 might not be repeated for several years. Many presume that the corn leafhopper will not overwinter as far north as New York, but, with climate change, that may be proven incorrect. There is much that we don’t know. Cornell University, Cornell Cooperative Extension, and the New York State Integrated Pest Management Program have committed to participate in a Corn Stunt Working Group of plant pathologists and entomologists in states affected by corn stunt and corn leafhopper. One aim of the group is to deploy a common protocol to monitor the corn leafhopper during the 2025 growing season. Also, the Cornell Plant Disease Diagnostic Clinic is gearing up to offer a molecular test for corn stunt spiroplasma in 2025.
How will the corn stunt disease complex be managed?
Awareness and accurate diagnosis of corn stunt and regional monitoring for corn leafhopper are necessary first steps in managing this complex. Based on limited observations in 2024, it appears that corn stunt could cause significant yield reductions under New York corn growing conditions. Plant breeding is the long-term solution to prevent corn yield losses. Hybrids with moderate resistance to the spiroplasma and / or the leafhopper have been deployed in Latin American countries to manage the corn stunt complex. International companies that sell seed in the U.S. as well as Latin America are aware of which germplasms are most promising for incorporation into hybrids for northern temperate areas such as ours. I do not expect much choice of resistance in northern hybrids in 2025. Management of corn leafhopper populations with insecticides at corn vegetative stages to reduce corn stunt deserves further investigation. My principal advice to New York growers in 2025 is to plant corn at the earliest recommended date to avoid arrival of leafhoppers at the most vulnerable plant stages for infection by spiroplasma.
Acknowledgements:
I gratefully acknowledge agronomist Rafaela Aguiar of Kreher Family Farms for her keen observation of corn stunt symptoms and her continuing cooperation. Colleagues Michael Stanyard (Cornell Cooperative Extension Northwest New York Dairy, Livestock, and Field Crops Program) and Michael Hunter (New York State Integrated Pest Management Program) were instrumental in collecting corn leaf samples and leafhoppers from additional sites in New York. Identification of corn leafhopper and corn stunt spiroplasma would not have been possible without the expert help of colleagues at Oklahoma State University including professors Maira Duffeck and Ashleigh Faris, and diagnostician Jennifer Olson.
Judith M. Kolkman1 , Rebecca J. Nelson1, 2, and Gary C. Bergstrom1 Sections of Plant Pathology and Plant-Microbe Biology1, and Plant Breeding and Genetics2 – School of Integrative Plant Science – Cornell University
What to know about BMR silage corn and diseases
Brown midrib (BMR) corn is a market class within silage corn that is desirable due to its significantly decreased lignin content. As the name suggests, midrib veins of BMR corn leaves have a distinctive brown color. Decreased lignin is desirable in corn silage because it increases feed digestibility for ruminant animals. BMR corn carries naturally derived mutations in single genes that affect the plant’s lignin biosynthetic pathway.
The biosynthetic pathway that produces lignin also makes compounds that contribute to active plant defense mechanisms. Some of these active defenses include small molecules called secondary metabolites that confer resistance against pests and diseases. Structurally, lignin is a major component of the cell wall and serves as a barrier against fungal pathogens. Lignin is also actively produced to strengthen cell walls that are being attacked.
To date, six BMR mutations have been identified in corn, and are designated as bm1 through bm6. The causal gene has been identified for five of the BMR mutations. Lines carrying two of these mutations, bm1 and bm3, are used as inbred parents for the production of commercially available hybrids known as BMR1 and BMR3, respectively. Commercial BMR silage corn hybrids have been gaining in popularity.
There is concern that the same bm gene(s) that confer greater digestibility to BMR silage hybrids may also confer increased susceptibility to fungal diseases. Some of these hybrids are more vulnerable to stalk lodging. Northern leaf blight severely affected commercial BMR hybrids in 2013 and other recent growing seasons.
To determine the effect of the brown midrib mutations on disease susceptibility, we used replicated trials across multiple years to test the reaction of bm1 – bm4 mutants in a uniform inbred line background, W64A, to leaf, stalk and ear diseases (Fig. 1, Fig. 2 and Fig. 3). Corn lines containing the four BMR mutations were all found to have heightened susceptibility to foliar fungal diseases, including northern leaf blight, gray leaf spot and anthracnose leaf blight (Fig. 1 and Fig. 2).
Figure 1. Examples of lesions of (left to right): northern leaf blight, anthracnose leaf blight, Stewart’s bacterial wilt and gray leaf spot in corn.Figure 2. Reactions to foliar fungal (NLB, GLS and ALB) and bacterial (SW) diseases in W64A inbred lines containing bm1, bm2, bm3 or bm4 mutations in comparison with W64A which does not contain a BMR mutation.Figure 3. Reactions to anthracnose stalk rot and Gibberella ear rot in W64A inbred lines containing bm1, bm2, bm3 or bm4 mutations in comparison with W64A which does not contain a BMR mutation.
Figure 4 depicts a dramatic increase in W64A with the bm3 mutation. The lines were also found to be more susceptible to the foliar bacterial disease, Stewart’s bacterial wilt (Fig. 2). After two years of trials, our evidence suggests that BMR corn inbreds have higher susceptiblity to anthracnose stalk rot as well (Fig. 3). Additionally, the bm1 and bm3 containing inbreds were more susceptible to Gibberella ear rot, caused by Fusarium graminearum, when compared to their non-BMR counterparts (Fig. 3).
Figure 4. Increased severity in an inoculated trial of northern leaf blight in a W64A corn inbred with the bm3 gene (right) compared to a W64A inbred lacking the mutant gene (left).
The benefits of BMR silage corn are huge for the dairy industry. While individual hybrids may vary, BMR corn, appears to be more susceptible to diseases than non-BMR corn. The degree of susceptibility does vary by bm mutation and specific pathogen (Fig. 2 and Fig. 3). Breeders are constantly working to improve disease tolerance, and disease ratings should be factored into hybrid choices. BMR hybrids in the market show a wide range of suceptibilities to individual diseases.
How to manage diseases in BMR silage hybrids
Knowing that BMR silage corn can be more vulnerable to foliar, stalk, and ear diseases means that a proactive and integrated strategy is needed to maintain optimal plant health in these hybrids. Elements of integrated management include:
Be aware of corn diseases on your farm and in your area. Scout your fields annually for foliar diseases from tassel emergence through grain formation. Check for ear rots (by pulling back husks) and stalk rots (squeeze lower stalks or attempt to push stalks over) prior to harvest. Seeing diseases even late in the season gives you an indication of what pathogens may survive in corn residues into the next growing season and helps you to plan rotations and select hybrids.
Fungi that cause anthracnose, gray leaf spot, northern leaf blight, and Gibberella ear rot and stalk rot survive between crop seasons in corn residues on the soil surface; therefore rotation of corn with non-host crops can help to reduce the spore inoculum potential for these diseases. Northern leaf blight has been the most widespread and injurious foliar disease in New York in the past decade and can be a problem anywhere in any given year.
Consider disease susceptibility when selecting BMR hybrids. Select BMR hybrids with the least susceptibility to specific diseases that have been problematic on your farm or in your region. If disease risk is extreme, e.g., in a humid river valley with a history of severe gray leaf spot, it may be preferable to grow non-BMR hybrids with documented resistance.
BMR hybrids, especially BMR1 and BMR3, have the potential to have severe ear rot and mycotoxin contamination in years with persistent moisture during silk emergence. Be sure to check seed company guides for the latest disease ratings for BMR hybrids.
Apply foliar fungicide based on disease detection and forecast risk. There is a wide choice of foliar fungicide products labeled for control of fungal leaf blights in New York. Table 3.5.1 in the 2020 Cornell Guide for Integrated Field Crop Management (https://www.cornellstore.com/2020-PMEP-Guide-for-Integrated-Field-Crop-Mgmt) notes the relative efficacy of labeled fungicides against different corn diseases. To slow down the development of resistance to fungicides in pathogen populations, it is best to use products with different modes of action (FRAC groups) in alternating years or to apply combination products with more than one mode of action.
The optimal timing for applying foliar fungicides is between tassel emergence (VT) and brown silk (R2) stages. Observation of foliar fungal diseases in the middle leaf canopy (at lowest ear level) and a forecast of significant precipitation in the following week are the best indicators that fungicide application will be result in disease suppression and yield increase. Suppression of foliar diseases also helps to preserve stalk health, standability, and quality, including lower levels of fungus-produced mycotoxins.
Consider longer term and regional effects of growing BMR hybrids. Year after year of growing a susceptible BMR hybrid can increase the disease inoculum load in a particular field and locale, thus affecting neighboring fields of non-BMR silage, dent, and sweet corn. Occasional rotation out of BMR corn should be considered.
Summary
BMR silage corn is increasing in popularity and acreage as it provides a high quality, digestible feedstock for dairy nutrition. Its positive attributes need to be balanced with proactive disease management to insure plant health and sustained productivity in dairy cropping systems.
Acknowledgements
This work was supported by the USDA National Institute of Food and Agriculture Hatch accession #1004040.
The full version of What’s Cropping Up? Volume 30 No. 3 is available as a downloadable PDF on issuu. This issue includes links to COVID-19 resources on the back page. And as always, individual articles are available below:
Gary C. Bergstrom, Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University
The Disease
Wheat spindle streak mosaic (WSSM), caused by wheat spindle streak mosaic virus (WSSMV), is a disease that attracts little attention today because most of our widely grown, winter wheat varieties have significant levels of resistance to it. Yet WSSMV persists in New York soils in its protozoan vector ready to infect the roots of susceptible winter wheat varieties soon after planting. Swimming spores (zoospores) of the vector move through films of water in the soil and thus root infection is favored by moist conditions in fall. Plants remain infected over the winter dormant period but do not develop typical leaf symptoms until spring following a number of weeks of cool weather which favors virus replication and virus movement from roots into shoots. Temperature, not moisture, is what drives symptom development in spring since plants were already infected in the fall. Only winter wheats, not spring wheats, are affected by WSSMV because of the time it takes to build up virus levels in the roots and then the shoots.
Symptoms
Symptoms of WSSM first appear in late April or early May and are characterized by long, light green, spindle-shaped streaks with dark centers (Fig. 1). As leaves age, these streaks can become necrotic and resemble lesions of Septoria tritici blotch but without dark fruiting bodies, i.e., pycnidia of Zymoseptoria, in evidence under a hand lens. Symptoms of WSSM fail to develop on new leaves that emerge when average daily temperatures exceed 60 F, though symptoms can reinitiate at later growth stages if persistent cool conditions occur during stem elongation, head emergence, and even grain-filling. Conditions have been ideal in April and May 2020 for development of WSSM. Symptom development is extremely sensitive to warm temperatures such that we have seen very little WSSM in years with high temperatures in early spring.
Figure 1. Characteristic symptoms of wheat spindle streak mosaic on wheat flag leaves at boot stage (A) and close-up of spindle streaks (B).
Management
What should a wheat producer do if she/he observes characteristic symptoms of WSSM this spring? There is no action that can be taken to mitigate WSSM in a growing crop – the yield damage, which can exceed 30% of the crop’s potential, has already occurred. However, diagnosis of the disease is a sure reminder that the variety they are currently growing is susceptible to WSSMV, and they need to choose a variety with at least moderate resistance for planting in the coming fall. This should elicit a conversation with your seed supplier about varieties resistant to WSSMV; some companies include that information on their website and in their seed catalogs but others do not. While the majority of available varieties express resistance to WSSMV, susceptible varieties appear in the seed market from time to time. Scores for WSSM also are included in winter wheat variety trial tabular results (https://blogs.cornell.edu/varietytrials/small-grains-wheat-oats-barley-triticale/small-grains-cultivar-trial-results/) from Cornell’s Small Grains Breeding Program in years when symptoms are observed.
If you find more pronounced mosaic and fewer distinct streak symptoms in a variety designated to be WSSMV-resistant, your wheat could be infected by another soilborne, protozoan-transmitted virus called soilborne wheat mosaic virus (SBWMV), which we have diagnosed occasionally in isolated fields in southern areas of the Finger Lakes Region. Resistance to SBWMV is independent from resistance to WSSMV, though it is also available from wheat seed suppliers in a choice of adapted varieties.
