Diseases
A group of fungi might fight a disease that’s dangerous to tomatoes and specialty crops. University of Florida scientists hope to develop this biological strategy as they add to growers’ tools to help control Fusarium wilt.

Using a $770,000, three-year grant from the USDA, Gary Vallad, associate professor of plant pathology, hopes to harness the advantages of fungi known as trichoderma to fight Fusarium wilt.

Vallad will work on the project with Seogchan Kang, Beth Gugino and Terrence Bell from the department of plant pathology and environmental microbiology at Pennsylvania State University and Priscila Chaverri from the department of plant science and landscape architecture at the University of Maryland.

Scientists hope to use trichoderma to supplement various pest-management methods to help control Fusarium wilt, Vallad said.

Trichoderma are ubiquitous fungi in soil and on plants, and they have been used in agriculture as biological control agents, he said.

UF/IFAS researchers have used trichoderma to try to control pathogens, but with little to no success. With this new round of research, they hope to understand what factors limit the fungus’ benefits as a biological control agent, Vallad said. That way, they hope to develop ways to increase its ability to control Fusarium wilt.

Growers began using other fumigants as methyl bromide was gradually phased out from 2005 until it was completely phased out of use in 2012, Vallad said. As growers tried various ways to control diseases, including alternative fumigants, they saw a re-emergence in soil-borne pathogens and pests on many specialty crops, including tomatoes, peppers, eggplant, watermelon, cantaloupes and strawberries, Vallad said.

When the project starts July 1, UF/IFAS researchers will do most of their experiments on trichoderma at the GCREC, but they’ll also use crops from commercial farmers during the project.

Vallad emphasizes that their research goes beyond Florida’s borders. Studies in Pennsylvania and Maryland will likely focus on small to medium-sized farm operations.

“We are focusing on tomato production Florida, Maryland and Pennsylvania,” he said. “We hope that our findings will help improve management of Fusarium wilt with trichoderma-based biological control agents.”
Published in Research
When humans get bacterial infections, we reach for antibiotics to make us feel better faster. It’s the same with many economically important crops. For decades, farmers have been spraying streptomycin on apple and pear trees to kill the bacteria that cause fire blight, a serious disease that costs over $100 million annually in the United States alone.

But just like in human medicine, the bacteria that cause fire blight are becoming increasingly resistant to streptomycin. Farmers are turning to new antibiotics, but it’s widely acknowledged that it’s only a matter of time before bacteria become resistant to any new chemical. That’s why a group of scientists from the University of Illinois and Nanjing Agricultural University in China are studying two new antibiotics—kasugamycin and blasticidin S—while there’s still time.

“Kasugamycin has been proven effective against this bacterium on apples and pears, but we didn’t know what the mechanism was. We wanted to see exactly how it’s killing the bacteria. If bacteria develop resistance later on, we will know more about how to attack the problem,” says Youfu Zhao, associate professor of plant pathology in the Department of Crop Sciences at U of I, and co-author on a new study published in Molecular Plant-Microbe Interactions.

The bacterium that causes fire blight, Erwinia amylovora, is a relative of E. coli, a frequently tested model system for antibiotic sensitivity and resistance. Studies in E. coli have shown that kasugamycin and blasticidin S both enter bacterial cells through two transporters spanning the cell membrane. These ATP-binding cassette (ABC) transporters are known as oligopeptide permease and dipeptide permease, or Opp and Dpp for short.

The transporters normally ferry small proteins from one side of the membrane to the other, but the antibiotics can hijack Opp and Dpp to get inside. Once inside the cell, the antibiotics attack a critical gene, ksgA, which leads to the bacterium’s death.

Zhao and his team wanted to know if the same process was occurring in Erwinia amylovora.

They created mutant strains of the bacterium with dysfunctional Opp and Dpp transporters, and exposed them to kasugamycin and blasticidin S.

The researchers found that the mutant strains were resistant to the antibiotics, suggesting that Opp and Dpp were the gatekeepers in Erwinia amylovora, too.

Zhao and his team also found a gene, RcsB, that regulates Opp and Dpp expression. “If there is higher expression under nutrient limited conditions, that means antibiotics can be transported really fast and kill the bacteria very efficiently,” he says.

The researchers have more work ahead of them to determine how Opp/Dpp and RcsB could be manipulated in Erwinia amylovora to make it even more sensitive to the new antibiotics, but Zhao is optimistic.

“By gaining a comprehensive understanding of the mechanisms of resistance, we can develop methods to prevent it. In the future, we could possibly change the formula of kasugamycin so that it can transport efficiently into bacteria and kill it even at low concentrations,” he says. “We need to understand it before it happens.”

The article, “Loss-of-function mutations in the Dpp and Opp permeases render Erwinia amylovora resistant to kasugamycin and blasticidin S,” is published in Molecular Plant-Microbe Interactions [DOI: 10.1094/MPMI-01-18-0007-R]. Additional authors include Yixin Ge, Jae Hoon Lee, and Baishi Hu. The work was supported by a grant from USDA’s National Institute of Food and Agriculture.
Published in Research
Comparison of fungicide programs:

In 2016 and 2017, Cheryl Trueman compared several different cucumber downy mildew control programs in plots at the University of Guelph Ridgetown Campus.

Different product rotations included:
  • Bravo-only applied 6 times.
  • A high input strategy that focused on optimal control and resistance management: Orondis Ultra A+B; Torrent; Zampro; Orondis Ultra A+B; Torrent; Zampro.
  • A low-input strategy that focused on early control and resistance management, switching to lower-cost fungicides in the final weeks of harvest: Orondis Ultra A + B (plus Bravo); Torrent; Zampro; Bravo; Bravo; Bravo.
  • A single application of Orondis Ultra, applied early followed by the other targeted downy mildew fungicides (Orondis Ultra A + B; Torrent ; Zampro; Torrent; Zampro; Torrent).
  • Control – no fungicides applied.
Results indicate that the highest level of control was achieved using a high input three product rotation of Orondis Ultra A+B, Torrent and Zampro when downy mildew pressure was high in 2016.

Under these conditions final yields for both the high input and single Orondis Ultra (in rotation) were both significantly higher than the Bravo only programs and yield for the high input program were significantly higher than all other treatments.

When pressure was moderate in 2017, the high input and single Orondis Ultra in rotation program were very effective. All fungicide programs except Bravo only increased both fruit number and yield by weight.
Published in Vegetables
Bayer announces the launch of Luna Sensation fungicide in Canada for stone fruit, root vegetables, cucurbit vegetables, leafy green vegetables, leafy petiole vegetables, brassica vegetables and hops.

The foliar product is a co-formulation of two fungicide modes of action, a unique Group 7 SDHI (fluopyram) and a proven Group 11 (trifloxystrobin) to deliver superior disease control, resulting in higher yields and exceptional fruit quality.

“Luna Sensation gives Canadian growers further access to the excellent disease control provided by Luna,” said Jon Weinmaster, crop & campaign marketing manager, corn & horticulture. “It’s designed for optimal efficacy on specific crops and diseases, most of which are not covered by the Luna Tranquility label, a product that has proven invaluable to many horticulture growers for several years already.”

Luna Sensation is a systemic fungicide that targets highly problematic diseases such as sclerotinia rot, powdery mildew, and monilinia.

It also has added benefits for soft fruit.

“Experiences of U.S. and Canadian growers show that Luna offers post-harvest benefits in soft fruit, improving quality during transit and storage”, says Weinmaster “It’s an added benefit that comes from excellent in-crop disease control.”

The addition of Luna Sensation from Bayer extends the trusted protection of the Luna brand to a broader range of crops:
  • Luna Tranquility, a Group 7 and Group 9 fungicide, is registered for apples, grapes, tomatoes, bulb vegetables, small berries and potatoes
  • Luna Sensation is registered for stone fruit, root vegetables, cucurbit vegetables, leafy green and petiole vegetables, brassica vegetables and hops
Luna Sensation will be available to Canadian growers for the 2018 season.

For more information regarding Luna Sensation, growers are encouraged to talk to their local retailer or visit: cropscience.bayer.ca/LunaSensation
Published in Diseases
Syngenta Canada Inc., is pleased to announce the registration of Revus fungicide as a potato seed treatment for the suppression of pink rot and control of seed‑borne late blight in potatoes.

Pink rot is a devastating, soil-borne disease caused by the pathogen Phytophthora erythroseptica that thrives in wet, poorly drained soils. Infection typically takes place pre-harvest, as the pathogen enters tubers through the stem end and lenticels.

Tubers infected with pink rot will often decay during harvest and handling, which allows the pathogen to spread quickly from infected tubers to healthy tubers while in storage.

“Every field has the potential for pink rot,” says Brady Code, eastern technical lead, with Syngenta Canada. “It takes a very small number of infected tubers going over harvest equipment or getting by on the belt to put an entire season of work in jeopardy and leave growers with far fewer healthy potatoes to ship.”

Revus contains the active ingredient mandipropamid (Group 40) and works by protecting the daughter tubers from becoming infected with pink rot.

“Growers can use Revus as part of an integrated approach to target fields where they’ve had pink rot issues in previous seasons, on their more susceptible varieties, and in tandem with other in-furrow and post-harvest fungicides,” explains Shaun Vey, Seedcare and Inoculants product lead with Syngenta Canada.

Vey adds that Revus also provides control of seed-borne late blight (Phytophthora infestans). Syngenta research demonstrates that potatoes treated with Revus for seed-borne late blight have nearly perfect emergence, while untreated seed potatoes infected with late blight have a 20 to 30 per cent reduction in emergence.

“Seed-borne late blight can have a big impact on emergence over time,” explains Vey. “When used as a seed treatment, Revus can help prevent seed piece decay and the spread of disease spores from seed piece to seed piece.”

Revus is applied at 5.9-11.8 mL per cwt of seed (13-26 mL/100 kg of seed).

Following a seed treatment application of Revus fungicide, the first foliar fungicide application should be a product that does not contain a Group 40 active ingredient.

Maximum Residue Limits (MRLs) for mandipropamid, have been established for markets including Canada, the United States, Japan, and South Korea, in support of the seed treatment use pattern.

For more information about Revus potato seed treatment, please visit Syngenta.ca; contact your local Syngenta Representative or our Customer Interaction Centre at 1‑87‑SYNGENTA (1‑877‑964‑3682).
Published in Diseases
Good nutrition is essential for supporting potato plant health and providing the necessary defense against plant disease and stress.

The International Plant Nutrition Institute (IPNI), J.R. Simplot Company, and Tennessee State University have collaborated on a new publication that provides readers with access to a unique collection of hundreds of high resolution photographs that document a wide range of nutrient deficiency symptoms in potato plants with remarkable clarity.

"IPNI is fortunate to collaborate with Dr. Pitchay and Simplot in producing this world-class collection of photographs and information," said Dr. Robert Mikkelsen, vice president, IPNI Communications and co-author of the book.

Developed within a unique greenhouse system at Tennessee State University, this collection provides examples of mild, moderate, and severe cases of deficiencies of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), boron (B), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn). The identification of nutrient deficiencies in the field can be a difficult process and this collection provides farmers, crop advisers, and mineral nutrition researchers with a valuable diagnostic tool. Once the underlying deficiency is known, strategies can be developed to help avoid losses in yield or crop quality.

“This has been a tremendous opportunity to work with leading scientists to develop a world class collection of fully documented photos describing the major crop nutritional problems commonly observed in the field,” explains Dr. Terry Tindall, director of agronomy for Simplot.

The book is now available to download from the IPNI Store. For more information, visit: http://info.ipni.net/ebooks

Published in Vegetables
Fredericton, N.B. - Dr. Claudia Goyer, a molecular bacteriologist at Agriculture and Agri-Food Canada’s Fredericton Research and Development Centre in New Brunswick, says she is seeing promising results that may help potato growers get more of their products into the global marketplace.

Common scab is a potato disease caused by bacteria in the soil and while it is not a health issue for humans, common scab’s crusty lesions on potato skin can make potatoes unmarketable. The allowable limit for the appearance of potato scab on a potato is five per cent.

Building on research done in Australia, Dr. Goyer has been working with Canadian tissue culture expert Dr. Vicki Gustafson to develop natural variations of Shepody and Red Pontiac varieties with greater scab resistance.

In the lab, the researchers bathed potato tissue samples in a plant toxin secreted by the microorganism that causes common scab. As expected, the toxin killed many of the tissue samples.

Among the survivors, they looked for samples that evolved with a resistance to the toxin, and hopefully to the microorganism that produces it.

“We’re tapping into a plant’s natural ability to spontaneously change or mutate in response to stress,” says Dr. Goyer.

From the surviving tissue samples, 50 were selected for field testing and ten of those have shown improved resistance.

The Red Pontiac offshoots have been particularly promising, with 50 per cent less incidence of common scab than in current Red Pontiac variety. Researchers have been seeing up to 30 per cent less common scab in the Shepody offshoots.

Dr. Goyer is encouraged by the results, but says the evaluations will need to continue for another two to three years before the new, more resistant offshoots of the Shepody and Red Pontiac can be brought to the market.

Published in Vegetables
February 7, 2018, Guelph, Ont – The Pest Management Regulatory Agency (PMRA) recently announced the approval of a minor use label expansion registration for Reason 500SC fungicide for control of downy mildew on basil and an amendment to update the label to include management of downy mildew on the new Brassica vegetable crop groups 5-13 and 4-13B in Canada.

The head and stem Brassica vegetable group includes cabbage, napa cabbage, Brussels sprouts, cauliflower and broccoli and the new Brassica leafy greens crop group includes arugula, Chinese broccoli, Chinese cabbage, bok choy, collards, cress, kale, mizuna, mustard greens, etc. Reason fungicide was already labeled for use on a number of crops in Canada for control of several diseases.

These minor use projects were submitted by Ontario as a result of minor use priorities established by growers and extension personnel.

Reason fungicide is toxic to aquatic organisms and may be harmful to beneficial predatory or parasitic arthropods. Do not apply this product or allow drift to other crops or non-target areas. Do not contaminate off-target areas or aquatic habitats when spraying or when cleaning and rinsing spray equipment or containers.

Follow all other precautions, restrictions and directions for use on the Reason fungicide label carefully.

For a copy of the new minor use label contact your local crop specialist, regional supply outlet or visit the PMRA label site https://www.canada.ca/en/health-canada/services/consumer-product-safety/pesticides-pest-management/registrants-applicants/tools/pesticide-label-search.html
Published in Diseases
January 22, 2018, Edmonton, Alta – There are a number of pests that affect potatoes in Alberta every year, to varying levels of severity, depending on the year, the type and market of potatoes, as well as the location.

Alberta Agriculture and Forestry, in partnership with the Potato Growers of Alberta, has organized a series of workshops for fresh/table, seed and processing potato growers in Alberta. Participants will receive information on a number of pests (insects, diseases, weeds) and their impact, identification and management in various types of potatoes. Expert speakers have been brought in (live or pre-recorded) from across North America.

Producers may attend one of two workshops in Sherwood Park (March 6) or Lethbridge (March 8). A maximum of two attendees from each farm operation may attend. The cost to attend these workshops is $15 per person (plus GST), which includes lunch and resource materials for each farm operation.

Participants are asked to register in advance by calling the Ag-Info Centre Registration line at 1-800-387-6030 prior to February 27, 2018 to assist with planning, or register on-line.
Published in Vegetables
January 2, 2018 – The science behind the home-pregnancy test is now being trialled to detect the presence of diseases that can devastate fields of vegetable crops, including Brussels sprouts.

Current trials are underway to help protect crops of Brassicas – sprouts, broccoli, cabbage – and onions. Diseases including ring spot, light leaf spot and downy mildew are being monitored.

Ring spot in Brassicas is a foliar disease, which if not treated can lead to the loss of 30 per cent of crop.

The test, known as a lateral flow device (LFD), picks up the presence of infective spores carried in the air around crops in the field. Used alongside weather data, test results could indicate how likely a disease is to develop, allowing growers to decide if crop protection methods are needed or not.

Further development work is underway, so growers can gain immediate results, without needing to send samples to laboratories for further testing. The project is the result of an industry partnership between growers, AHDB Horticulture, Warwickshire College and Mololgic Ltd.

“When it’s fully developed, this simple low-cost tool, allowing growers to test whether there is a risk of diseases developing on their crops, will help prevent significant financial losses and reduce the need to use conventional methods to protect their crops,” said Cathryn Lambourne, senior scientist with AHDB. “Over the last four years, we’ve been developing the lateral flow device test, demonstrating how simple and effective it is, to give growers the confidence to rely on the results and make appropriate decisions for their business.”

“This could be a big game changer for growers,” added Carl Sharp, an agronomist at the Allium and Brassica Centre. “If we can get kit like this developed to take out with us, within ten minutes of walking into a field, growers will have results which show what they need to do to protect their crops.” 

Downy mildew in onions can cause damage of up to 50 per cent of individual crops if severe and, in a particularly bad year, the whole industry could see crop losses of up to 25 per cent. This same disease could wipe out a whole field of salad onion.

“The long period between the disease affecting the crop and the symptoms appearing, which are a characteristic of many of the diseases tested, can lead to devastating diseases becoming established in crops turning them into waste,” said Euam Alexander, field operations manager with Kettle Produce in the UK. “Using these tests will allow us to select the appropriate fungicide and time application as part of our crop management strategy, before the disease renders any of the crops unmarketable.”

In addition to the common pregnancy test, LFDs are used to detect human diseases including colo-rectal cancer, cardiac issues and drug abuse screening.

The LFD tests are also being developed to detect for other plant diseases. The AHDB is funding the University of Worcester to develop lab tests and LFDs to test for oomycete pathogens, which cause diseases like blight and sudden oak death. Primarily testing is focused on root, stem and crown rots caused by Pythium and the Phytophthora species, commonly known as ‘the plant destroyer’, which can affect a range of crops. 

Through the same funding, Warwickshire Colleges and Stockbridge Technology Centre are developing and testing two LFDs to test glasshouse air samples for powdery mildew and gummy stem blight, which affect cucumber crops. Canker in apple tree crops is being investigated in a separate research program.
Published in Research
December 20, 2017, Saguenay, Que – Common scab is one of the most important diseases affecting potato crops worldwide. But researchers with the Université du Québec à Chicoutimi have discovered that using fresh residues and/or bio-products from Canadian goldenrod (Solidago canadensis) may offer an alternative to conventional fumigants.

In the study, researchers conducted a preliminary investigation of the utilization of S. canadensis to reduce common scab severity, and determined the allopathic potentials of S. canadensis extracts on Streptomyces scabiei (also known as S. scabies).

Compared with control plants, preliminary results showed that adding 1.2 kg of fresh S. canadensis residue per m2 reduced scab severity by about 45 per cent. Furthermore, concentrations of hexane and dichloromethane extracts from S. Canadensis inhibited the growth of S. scabiei by about 97 per cent.

The results were comparable with those using tetracycline, a known inhibitor of S. scabiei.

Both experiments suggested that S. canadensis may represent a new approach for controlling potato common scab. More studies are required to better understand the mechanisms involved in S. canadensis induced reduction of common scab in order to standardize the approaches.
Published in Research
December 12, 2017, Guelph, Ont – Syngenta Canada Inc. recently announced that Orondis Ultra fungicide is now available in a premix formulation.

Orondis Ultra combines mandipropamid (FRAC Group 40) with oxathiapiprolin (FRAC Group 49) to provide protection against late blight (Phytophthora infestans).

Orondis Ultra works through translaminar and acropetal activity, moving across the leaf surface as well as upwards into new growth via the plant’s xylem, or water-conducting vessels. Both modes of action protect the plant during periods of active growth.

Previously, a case of Orondis Ultra contained two components – Orondis Ultra A and Orondis Ultra B – that required individual measuring and tank mixing.

Now, the new premix formulation has a single product label, meaning the components no longer require mixing prior to use, and will be available in a 4 x 3.78 L case.

“Weather conditions in-season can create the conditions needed for late blight to develop and thrive,” explains Eric Phillips, product lead for fungicides and insecticides with Syngenta Canada. “The new Orondis Ultra premix formulation helps make proactive late blight management more convenient for growers.”

Orondis Ultra is also registered for aerial application in potatoes.

In addition to potatoes, Orondis Ultra can be used on head and stem brassica vegetables, including broccoli and cabbage, bulb vegetables, such as onion and garlic, leafy vegetables, such as arugula and celery, and cucurbit vegetables, including cucumber and squash. See the Orondis UItra label for a complete list of crops and diseases.

Orondis Ultra will be available for purchase as a premix formulation for the 2018 season.

For more information about Orondis Ultra, visit Syngenta.ca, contact your local Syngenta representative or call 877-964-3682.
Published in Diseases
December 8, 2017, Mississauga, Ont – Bee Vectoring Technologies recently announced successful trial results in blueberries.

The trial was conducted near Parrsborough, NS, in low bush blueberries with the Wild Blueberry Research Program at Dalhousie University. The trial utilized BVT's newly developed honeybee system, consisting of a honeybee hive outfitted with dispenser technology through which BVT's proprietary plant beneficial microbe, BVT-CR7, can be delivered to crops. The trial was designed to determine the effectiveness of the BVT technology in controlling Botrytis blight (gray mold) and Monilinia blight (mummy berry), two common and devastating diseases affecting blueberry crops across North America, compared to untreated control and current chemicals standards. The trial also examined increases in productivity of the crop measured by marketable yield.

"Our yields went up quite substantially when we used the BVT system, whether alone or in combination with chemical fungicides, but they didn't go up where we used the fungicide alone," said Dr. David Percival, blueberry research program director and professor at Dalhousie University in Nova Scotia. "I was really surprised by the first results. I went back and double-checked the raw yield data, then the spreadsheet to make sure the statistical program was correct. The results indicate the potential for floral blight disease control and increased berry yields with the use of BVT technology. Future work will allow us to fine tune the use recommendations."

“These are excellent results once again for the company and firmly establishes another major market opportunity,” said Ashish Malik, CEO of BVT. “Notably, this was the first time we tested our honeybee delivery system in a replicated R&D study, and we got great results. Having a proven system that works with honey bees alongside our first system designed to work with commercial bumble bee hives allows us to reach a far wider market and gives us options to deliver solutions for growers based on the specific needs for their crops."

Blueberries are a high-value crop, fetching as much as US $18,000 in revenue per acre in certain regions. There are almost 300,000 acres of blueberries cultivated in the US and Canada with total farm gate value of US $ 1.1 billion. Blueberry production in North America represents 54 per cent of the worldwide cultivation of the crop with key growing regions including the Atlantic provinces and British Columbia in Canada, Washington, Oregon, Georgia, Michigan, California, North Carolina, New Jersey, and Florida in the U.S.
Published in Research
November 14, 2017, Edmonton, Alta – The HortSnacks-to-Go 2017/2018 webinar series continues on November 20, 2017, with Using Biocontrols in Field Scale Fruit and Vegetable Crops.

“Presenter Ronald Valentin is North America technical lead at Bioline AgroSciences,” says Dustin Morton, commercial horticulture specialist with Alberta Agriculture and Forestry. “He’ll be looking at how other areas of the world are using biological controls in field scale vegetable and fruit crops and how Alberta producers can take advantage of this growing area.”

The webinar takes place at 1:30 p.m. MT and there is no charge to attend. To register, email Dustin Morton or go to https://attendee.gotowebinar.com/register/8212513318118325250
Published in Insects
An apple a day may keep the doctor away, but the mould on it could destroy the fruit in storage.
Published in Production
September 5, 2017, Netherlands - In a hidden experimental field in Wageningen, the Netherlands, surrounded by tall maize plants, there are several smaller plots with potato plants.

In some of these plots there are only dead plants, in others the plants have been affected by late blight (Phytophthora infestans) to a greater or lesser extent, but there are also fields with only perfectly healthy potatoes.

The latter are the result of the latest crosses by the Wageningen company, Solynta. The breeders have succeeded, thanks to their revolutionary hybrid breeding technique, in making potato plants insusceptible to the dreaded potato disease.

A new way of potato breeding

Potatoes are generally clone-bred and grown vegetatively. A seed-potato is put in the ground, which produces some ten new potatoes. One of the disadvantages of this system is that the parent plant transmits diseases to the offspring. Also, making the crop resistant is a long process.

Solynta has therefore selected a whole new approach: the company developed hybrid breeding with elite parent-lines, which allow propagation with true seeds. READ MORE
Published in Research
August 30, 2017, California - The Public Strawberry Breeding Program at the University of California, Davis, and colleagues in California and Florida have received a $4.5 million grant from the National Institute of Food and Agriculture of the U.S. Department of Agriculture to improve the disease resistance and sustainable production of strawberries throughout the nation.

The collaborative grant is good news for strawberry farmers and consumers everywhere, according to Rick Tomlinson, president of the California Strawberry Commission. To signal its own support, the strawberry commission pledged an additional $1.8 million to the UC Davis program.

“An investment in the UC Davis strawberry breeding program is an investment in the future of strawberries,” Tomlinson said. “Thanks to their groundbreaking research and strong partnerships, Director Steve Knapp and his colleagues are developing improved strawberry varieties publicly available to farmers.”

Improving genetic resistance to disease

Strawberries constitute a $4.4 billion-dollar industry in the United States, and 94 percent of the nation’s strawberry fruit and nursery plants are grown in California and Florida.

Strawberries are especially vulnerable to soil-borne pathogens, which destroy plants and greatly reduce yield. Since the 1960s, strawberry growers have depended on fumigants like methyl bromide to treat soils before planting berries in an effort to control disease. But methyl bromide has been phased out by the Environmental Protection Agency and will no longer be available after 2017.

“Following the elimination of methyl bromide fumigation, strawberry growers are under greater economic pressures, and there is an urgent need for improved, disease-resistant strawberry varieties that will thrive without fumigation,” Knapp said.

Knapp will head a team of scientists from UC Davis, UC Santa Cruz, UC Riverside, the UC Division of Agriculture and Natural Resources, Cal Poly San Luis Obispo, and the University of Florida.

Together, researchers will identify and manage pathogen threats, mine elite and wild genetic resources to find natural sources of resistance to pathogens, and accelerate the development of public varieties resistant to a broad spectrum of disease and other pests.

“Strawberry growers are faced with the need to deliver high-quality fruit to consumers year-round, while protecting the environment, fostering economic growth in their communities and coping with profound changes in production practices,” Knapp said. “We look forward to collaborating with our industry partners through research, agricultural extension and education to help them reach those goals.”

UC Davis Public Strawberry Breeding Program

During six decades, the UC Davis Public Strawberry Breeding Program has developed more than 30 patented varieties, made strawberries a year-round crop in California and boosted strawberry yield from just 6 tons per acre in the 1950s to 30 tons per acre today.

Knapp took over directorship of the program in 2015. He and his team are working to develop short-day and day-neutral strawberry varieties; studying the genetics of disease-resistance, fruit quality and photoperiod response; and applying genomic techniques to make traditional strawberry breeding more efficient. They have 10 public varieties in the pipeline and plan to release one or two new strawberry varieties later this year.

Initiative collaborators

The grant is funded by USDA’s Specialty Crop Research Initiative. Collaborators from UC Davis include agricultural economist Rachael Goodhue, plant pathologist Thomas Gordon, and plant scientists Julia Harshman and Thomas Poorten.

Other key collaborators are Oleg Daugovish with UC Agricultural and Natural Resources; Alexander Putman at UC Riverside; Julie Guthman at UC Santa Cruz; Gerald Holmes and Kelly Ivors, both at Cal Poly; and Seonghee Lee, Natália Peres and Vance Whitaker, all of the University of Florida.
Published in Research
August 16, 2017, Ottawa, Ont. - Canadian fruit growers need the best varieties of plants to be successful. In the case of Canadian strawberry growers, they grow the best varieties of plants, which foreign buyers demand. The import and export of fruit plants, however, must go through the Canadian Food Inspection Agency (CFIA) to test for potentially devastating plant viruses. Currently, this testing and quarantine process takes an average of three years to complete, significantly hampering the speed of trade.

Today, the Honourable Lawrence MacAulay, Minister of Agriculture and Agri-Food, announced that the CFIA will lead two projects worth $500,000 that use new DNA-based technologies to reduce the quarantine testing time, helping to boost trade and economic competitiveness in the $240 million Canadian fruit tree industry.

"Together with provincial partners and industry, our government is making the investments in innovative science that enables agriculture to be a leading growth sector of Canada's economy. Together we can help meet the world's growing demand for high-quality, sustainable food and help grow our middle class," Minister MacAulay, said. 

The first project will dramatically shorten the testing period of seeds, cuttings and bulbs imported into Canada to grow new varieties of plants. With this funding, scientists will use DNA technology to test for all viruses associated with imported plants to get an early indication of any plant diseases present. This approach could reduce the quarantine testing time by up to two and a half years.

The second project streamlines the testing of strawberry plants. Traditionally, multiple tests for viruses are required before exporting strawberry plants to foreign markets. This project will test for multiple viruses in one single test, dramatically reducing the time and cost to get plants to market.

Funding for these projects is provided through a partnership between the CFIA, Genome British Columbia, Summerland Varieties Corporation, Phyto Diagnostics, the British Columbia Cherry Association, and Vineland Research and Innovations Centre.

"Canadian import/export markets will be stronger and more competitive because of these genomics-based tools. Early detection of pathogens and viruses is a vital outcome of genomics and it is being applied across many key economic sectors." Dr. Catalina Lopez-Correa, Chief Scientific Officer and Vice President, Genome British Columbia said. 
Published in Fruit
July 26, 2017, Ontario - Stemphylium leaf blight (Stemphylium vesicarium) of onion starts as yellow-tan, water-soaked lesions developing into elongated spots. As these spots cover the entire leaves, onions prematurely defoliate thereby reducing the yield and causing the crop to be more susceptible to other pathogens.

Stemphylium was first identified in Ontario in 2008 and has since spread throughout the Holland Marsh and other onion growing areas in southwestern Ontario.

Stemphylium leaf blight can sometimes be misdiagnosed as purple blotch (Alternaria porri), as they both have very similar symptoms initially. Purple blotch has sunken tan to white lesions with purple centers while Stemphylium tends to have tan lesions without the purple centers.

Stemphylium spores are dispersed by wind. Spore sampling at the Muck Crops Research Station using a Burkard seven-day spore sampler detected an average of 33 spores/m3 in 2015 and seven spores/m3 in 2016.

In ideal conditions, leaf spot symptoms occur six days after initial infection. Stemphylium tends to infect dead tissue or wounds, often as a result of herbicide damage, insect feeding or from extreme weather.

Older onion leaves are more susceptible to infection than younger leaves and symptoms are traditionally observed after the plants have reached the three- to four-leaf stage.

Over the last few years, Botrytis leaf blight (Botrytis squamosa) has become less of an issue and has been overtaken by Stemphylium as the most important onion disease — other than maybe downy mildew.

This may be because the fungicides used to target Stemphylium are likely managing Botrytis as well. Since Stemphylium can be so devastating and hard to control, fungicides are now being applied earlier in the season which may be preventing Botrytis to become established.

Botrytis squamosa overwinters as sclerotia in the soil and on crop debris left from the previous year and infects onions in mid-June when temperatures and leaf wetness are favourable for infection. In the Holland Marsh, Stemphylium lesions were first observed on June 29, 2015 and July 7, 2016.

The primary method of management is through foliar fungicides such as Luna Tranquility, Quadris Top and Sercadis. Keep in mind that Sercadis and Luna Tranquility both contain a group 7 fungicide so remember to rotate and do not make sequential applications.

The effectiveness of these fungicides in the future depends on the spray programs you choose today. There are already Stemphylium isolates insensitive to several fungicides in New York so resistance is a real and very serious issue with this disease.

Remember to rotate fungicide groups with different modes of actions to reduce the possibility of resistance. A protective fungicide is best applied when the onion crop has reached the three-leaf stage, however it may not be necessary in dry years.

Research is currently being conducted at the Muck Crops Research Station to improve forecasting models to identify the optimal timing for commercial growers to achieve good control.

BOTCAST disease forecasting model is available in some areas of Ontario to help growers predict the activity of the disease. Warm, wet weather between 18-26°C is most favourable for disease development. Regular field scouting is still the best method to assess disease levels.

Plant spacing that permits better air movement and irrigation schedules that do not extend leaf wetness periods may be helpful in some areas. Recent work at the Muck Crops Research Station has shown that spores increase two to 72 hours after rainfall with eight hours of leaf wetness to be optimal for the pathogen. Irrigate overnight if possible so by morning the leaves can dry out and you don’t prolong that leaf wetness period.

To lower inoculum levels it is crucial to remove or bury cull piles and to bury leaf debris left from the previous year’s crop through deep cultivation. Stemphylium of onion has many hosts including leeks, garlic, asparagus and even European pear.

Take the time to rogue out volunteer onions or other Allium species in other crops nearby and remove unnecessary asparagus or pear trees to lower inoculum levels. As with any other foliar disease of onion, it is beneficial to rotate with non-host crops for three years.

To prevent the development of resistance, it is essential to always rotate between different fungicide groups and/or tank mix with a broad spectrum insecticide. Current products registered for Stemphylium leaf blight of onion are listed by fungicide group below:

Group 7 - Sercadis

Group 7/9 - Luna Tranquility

Group 11/3 - Quadris Top
Published in Diseases
July 25, 2017, Ontario - The Pest Management Regulatory Agency (PMRA) recently announced the approval of URMULE registrations for Confine Extra fungicide (mono and di-potassium salts of phosphorus acid 53%) for the suppression of bacterial leaf spot (Xanthomonas campestris p.v. vitians) on leaf lettuce in Canada.

Where possible, rotate the use of Confine Extra (Group 33) with fungicides that have different modes of actions. Apply at a rate of 7 L/ha in a minimum of 100 L of water/hectare. Use a maximum of 6 foliar applications per growing season. Pre-harvest Interval (PHI) is 1 day.

Confine Extra is currently registered for downy mildew of lettuce, endive, radicchio as well as most brassica crops.

Follow all other precautions and directions for use on the Confine Extra label carefully.

For a copy of the new minor use label visit the PMRA label site: http://pr-rp.hc-sc.gc.ca/ls-re/index-eng.php
Published in Diseases
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