Diseases
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
July 14, 2017, Gainesville, FL – Some people love to eat a juicy, seedless watermelon for a tasty, refreshing snack during a hot summer day. University of Florida scientists have found a way to stave off potential diseases while retaining that flavour.

Consumers increasingly savour the convenience and taste of seedless watermelons, said Xin Zhao, a UF Institute of Food and Agricultural Sciences associate professor of horticultural sciences and lead author of a new study examining rootstocks, flavour and texture of watermelons.

Many growers produce seedless cultivars because that’s what consumers want, and it’s important to maintain the fruit’s yield and taste, as seedless cultivars might be more susceptible to fusarium wilt, a major soil-borne disease issue in watermelon production, Zhao said.

For the study, UF/IFAS researchers grafted seedless watermelon onto squash rootstocks to ward off soil-borne diseases, such as fusarium wilt. In plant grafting, scientists call the upper part of the plant the scion, while the lower part is the rootstock. In the case of vegetable grafting, a grafted plant comes from joining a vigorous rootstock plant – often with resistance or tolerance to certain soil-borne pathogens – with a scion plant with desirable aboveground traits.

Grafting is a useful tool to manage soil-borne diseases, but in this study, researchers were concerned that if they grafted watermelon onto squash rootstocks, they might reduce its fruit quality and taste. Overall, study results showed no loss in taste and major fruit quality attributes, like total soluble solids and lycopene content, Zhao said. Consumers in UF taste panels confirmed the flavour remained largely consistent between grafted and non-grafted plant treatments under different production conditions.

Furthermore, said Zhao, compared with the non-grafted seedless watermelons, plants grafted onto the squash rootstocks exhibited a consistently higher level of flesh firmness.

“We are continuing our grafted watermelon research to optimize management of grafted watermelon production, maximize its full potential and seek answers to economic feasibility,” she said.

Still to come is a paper that specifically tells researchers whether they warded off fusarium wilt under high disease pressure, Zhao said. Grafting with selected rootstocks as a cultural practice is viewed as an integrated disease management tool in the toolbox for watermelon growers to consider when dealing with fusarium wilt “hot spots” in the field, she said. However, most squash rootstocks are generally more susceptible to root-knot nematodes, a potential challenge with using grafted plants. Other UF/IFAS researchers are tackling that issue.

The new UF/IFAS study is published in the Journal of the Science of Food and Agriculture.
Published in Research
June 19, 2017, Agassiz, BC – Dr. Rishi Burlakoti has joined the Agassiz Research and Development Centre (ARDC), bringing with him more than 10 years of experience in plant pathology. His research will address the new and existing diseases of high value horticultural crops, focusing mainly on small fruits and vegetable crops.

Prior to joining the ARDC team, Dr. Burlakoti led the mycology and bacteriology units at the World Vegetable Centre in Taiwan. He focused on global fungal and bacterial diseases of solanaceous vegetables (e.g. tomato, pepper, eggplant). From 2010 to 2016, he worked as a plant pathologist and research lead at Weather Innovations Consulting LP, an agricultural consulting company based in Ontario, where he led several applied research projects and provided consulting services to sector organizations and agri-food businesses in Canada, the United States, and Europe. Dr. Burlakoti also worked as a Postdoctoral scientist in the Wild Blueberry Research Program at Dalhousie University in 2009, and in the Barley Pathology Program at North Dakota State University in 2008.

Dr. Burlakoti is serving as an editor for two international journals: Plants and Archives of Phytopathology and Plant Protection. He is also a member of the Canadian Phytopathological Society, the American Phytopathological Society, and the Canadian Society for Horticultural Science. He is an adjunct faculty at Plant Agriculture, University of Guelph.

Dr. Burlakoti will be at the ARDC’s open house on July 22. Drop by to meet him and the rest of the centre’s staff as we celebrate Canada’s 150th birthday. Alternatively, you can reach him at This e-mail address is being protected from spambots. You need JavaScript enabled to view it or 604-796-6011.
Published in Research
June 15, 2017, Guelph, Ont. - It seems like recently there have been a rash of proposed or pending pesticide regulation changes that affect field growers, and tomato growers are no exception.

There are re-evaluations ongoing for a number of products used in tomatoes, including mancozeb, neonicotinoids, and Lannate, as well as Ethrel, but the big one that comes to mind for field tomato growers is the proposed changes to the use of chlorothalonil (Bravo, Echo).

The final outcome of this review is not yet known, but it’s likely that significant changes to the chlorothalonil labels are coming.

Chlorothalonil is a go-to fungicide for tomato growers. Data from trials at Ridgetown Campus demonstrate its value. Chlorothalonil is often just as good at controlling early blight, Septoria leaf spot, and anthracnose fruit rot as alternative fungicides, and it also provides protection from late blight, which many targeted fungicides do not.

It’s a good value active ingredient for tomato disease management and has a low risk of resistance development. But, if proposed changes go through, the number of chlorothalonil applications you can use will be drastically cut. READ MORE 
Published in Chemicals
May 9, 2017 – Laboratory testing can detect Dickeya — but is there enough of it present to justify the higher costs?

It’s a relatively new threat to North American potato production. The invasive pathogen Dickeya dianthicola — not to be confused with blackleg causing Dickeya solani — was first spotted in Canada in Ontario fields, having come in on seed potatoes from Maine. READ MORE
Published in Vegetables
May 9, 2017, Guelph, Ont – The Ontario Ministry of Agriculture, Food and Rural Affairs is again developing fire blight risk maps during the 2017 apple and pear blossom period based on the Cougarblight Model to help support apple and pear growers with their fire blight management decisions.

The risk is based on inputting the seven-day weather forecasts from 67 locations from various regions throughout the province into the Cougarblight model. The results from Cougarblight are then mapped and posted on the OMAFRA Website.

This year, there will be a separate webpage for apples and pears (in English and French).

The maps are animated and will cycle through the seven-day fire blight risk predictions based on the seven-day weather forecast. Updated fire blight risk prediction maps will be generated and posted three times per week (Monday, Wednesday and Friday) until bloom period is over. A new feature on the maps will allow growers to zoom in and out of the maps, reposition them to their specific locations and pause or start the maps.

As with any model, the fire blight risk is a general guide and environmental conditions may be more conducive for fire blight infection in a particular orchard than what is indicated by the maps. All apple and pear growers are encouraged to run either the Cougarblight or Maryblyt model with data generated from their orchards for a more accurate prediction.

Assumptions: The risk assumes that open blossoms are present and dew or rain will wet the blossom, which is necessary for a fire blight infection to occur. If there are no open blossoms or if wetting of the open blossoms does not occurs, infection will most likely not take place. However, it only takes a little dew to wash the fire blight bacteria into the open blossom for infection to occur.

How to use the maps: There are only two maps that will be generated this year, one for 'fire blight occurred in the neighbourhood last year' and another for 'Fire blight occurred in the orchard last year and is now active in your neighbourhood'. To use the maps, orchards must be assigned to one of two categories based on the fire blight situation in the orchard last year and this year.
  1. Fire blight occurred in the orchard last year and is now active in your neighbourhood (use the 1st map labeled 'Active Fire Blight in Apples 2017')
  2. Fire blight occurred in the neighbourhood last year (use the 2nd map labeled 'Fire Blight Occurred Last Year in Apples')
If the fire blight situation from last year is not known, it is best to assign the orchard to 'Fire blight occurred in the neighbourhood last year' and follow the 2nd map on the webpage. Once the orchard has been assigned to one of the categories above, locate the region of the orchard on the fire blight risk prediction maps and follow the animated maps for the predicted fire blight risk corresponding to the dates on the map. The animated maps will change through the changing risks over the seven day forecast, so watch them carefully. A brief interpretation of the risk will be posted above the maps for each update.

Interpretation of Risk: The following risks (Legend) are colour coded on the maps and designated as follows:
  • Low (green): Indicates a low risk of fire blight occurring. Wetting of blossoms during these temperature conditions has not resulted in new infections in past years.
  • Caution (orange): Wetting of flowers under these temperature conditions is not likely to lead to infection except for blossoms within a few meters of an active canker. Risk of infection will increase if the weather becomes warmer and wetter. Weather forecasts should be carefully monitored. If antibiotic materials are not being used, blossom protection with other materials should be initiated one or two days prior to entering a high infection risk period. Continue appropriate protective sprays until the infection risk drops below the "high" threshold.
  • High (purple): Under these temperature conditions, serious outbreaks of fire blight have occurred. Orchards that recently had blight are especially vulnerable. The risk of severe damage from infection increases during the later days of the primary bloom period, and during petal fall, while blossoms are plentiful. Infection is common, but more scattered when late blossoms are wetted during high-risk periods. The potential severity of infection increases if a series of high-risk days occur.
  • Extreme and Exceptional (magenta): Some of the most damaging fire blight epidemics have occurred under these optimum temperature conditions, followed by blossom wetting. Orchards that have never had fire blight are also at risk under these conditions. Infections during these conditions often lead to severe orchard damage, especially during primary bloom or when numerous secondary blossoms are present.
Published in Fruit
May 4, 2017, Brandon, Man – Whether fresh or processing potatoes, any issue in storage needs to involve partnership with your end-user, says Mary LeMere, an agronomy manager with McCain Foods based in Wisconsin.

LeMere was at Manitoba Potato Production Days in Brandon, Man., January 24 to 26 to deliver “lightning advice” on three key topics – managing late blight in storage, the impact of pile height on potato quality, and tips for using FLIR cameras to detect issues in the pile. READ MORE
Published in Vegetables
May 1, 2017, Orono, ME — Two bacteria threatening the potato industry worldwide will be the focus of a Potato Disease Summit Nov. 9 in Bangor, Maine, convened by the University of Maine.

Plant pathologists, researchers and scientists from The Netherlands, Scotland and five U.S. states will present the latest information on the bacteria — Dickeya and Pectobacterium — that cause blackleg disease, an emerging potato seed problem.

In the past three growing seasons, Dickeya, a bacterial pathogen of potatoes, has caused significant economic losses in seed nonemergence and crop loss nationwide. In addition, an associated pathogen, Pectobacterium, has caused potato crop losses in the field and in storage. The bacteria have caused losses to the potato industry in Europe for an even longer period.

"The University of Maine is responding to this situation by holding an international summit focused on the latest research and what steps are needed to help the potato industry," says University of Maine President Susan J. Hunter. "As Maine's only public research university, we are a longstanding partner with the state's potato industry in addressing its needs, including the growing threat posed by Dickeya and Pectobacterium."

The Potato Disease Summit – being held 8 a.m. to 5 p.m., Nov. 9 at the Cross Insurance Center, 515 Main St., Bangor, Maine – is designed for scientists, consultants, regulatory officials, and potato seed growers and buyers. It will focus on such topics as current advances in detection and diagnosis of Dickeya; an overview of Pectobacterium in the U.S.; and management of Enterobacteriaceae spread and risk.

The $80 per person fee includes materials, lunch and breaks. Registration deadline is Oct. 2 and is available online: extension.umaine.edu/agriculture/programs/dickeya-and-pectobacterium-summit/.

For more information or to request a disability accommodation, contact Steve Johnson, 207.554.4373, This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
Published in Research
April 21, 2017, Morgantown, WV - Gallegly, West Virginia University professor emeritus of plant pathology, has made it his mission to develop a disease-free tomato.

Gallegly and his research partner, Mahfuz Rahman, released two new varieties of tomato.

The tomatoes, identified as West Virginia ’17A and West Virginia ’17B, were obtained by breeding the tomatoes known as the West Virginia ’63 and the Iron Lady.

Gallegly developed the W.Va. ’63 tomato in the 1960s as a tomato resistant to late blight, a plant disease usually caused by fungi. The Iron Lady tomato, developed by Martha Mutschler-Chu of Cornell University, also resists late blight but also Septoria lycopersici, a fungus that causes spotting on leaves.

Gallegly said the stink bug, specifically the marmorated stink bug, is the likely cause of Septoria increasing on tomatoes.

“We just crossed the two tomatoes and in the second generation in the field, we made selections for fruit type, yield, taste and so on,” Gallegly said. “So we came up with two new varieties.”

Through their evaluation, the two tomatoes should have a higher tolerance to Septoria leaf spot and better fruit quality.Tomatoes are a specialty of Gallegly, who turns 94 this month.

He came to the University in 1949 as an assistant professor and was hired to become the vegetable plant pathologist for the state.

He spent his first fall and winter at the university collecting varieties of tomatoes and potatoes. The next year, he planted varieties of the two vegetables and discovered late blight was severe that year. So much so that he had zero tomato yield.

“That told me I had to go to work on trying to control this disease,” he said.

After 13 years of screening the vegetables and research, he came up a new tomato in 1963 — the West Virginia ’63.

Gallegly officially retired from the University in 1986 but earned emeritus status and kept a presence at the college to continue research and teaching.

On March 24, the two new tomatoes were unveiled during the annual Potomac Division of the American Phytopathological Society meeting in Morgantown. READ MORE
Published in Research
April 19, 2017 – Healthy seed is a key factor in growing a quality potato crop. Several diseases affect seed tubers and have the potential to reduce plant stand early in the season.

It is extremely important to examine all seed lots carefully immediately after receiving the seed.
If you detect diseases or defects, check the standards set by the Canadian Food and Inspection Agency (CFIA). There are tolerances both for shipping and for receiving.

If diseases or defects appear to be a problem, growers may request that an inspector from CFIA re-inspect the seed, but this must be done within 48 hours of receiving the seed.

Disinfesting the seed cutters often is strongly recommended to reduce the spread of pathogens.

Important seed-borne diseases that reduce plant stand.

Fusarium dry rot (Fusarium spp)
This is the most common disease causing seed piece decay. Infected seed pieces may be partially or completely destroyed. A single sprout may emerge if only part of the seed piece is infected, but the resulting plant will be weak and will produce few marketable tubers.

Fusarium lesions are sunken and shriveled with concentric wrinkles. The internal rotted tissue is brown or grey to black, dry and crumbly. There is no noticeable smell. Fusarium often rots the center of the tuber, forming a cavity. The walls of the cavity are often lined with rotting tissue, producing spores that may be white or yellow or pink. Fusarium spores can contaminate healthy seed at cutting and spread the disease to healthy tubers. There are seed-piece treatments to prevent the spread of Fusarium during seed cutting, but no seed treatment can turn bad seed into good.

Rhizoctonia (R. solani)
Rhizoctonia can reduce plant stands and cause serious losses especially in cool springs. Affected tubers have sclerotia, which are black, irregular lumps stuck to the tuber skin. These black sclerotia germinate producing a fungal growth that infects sprouts causing dark brown cankers. Infections that kill sprouts before emergence cause severe damage. New sprouts will emerge, but they will be less vigorous than the first sprouts resulting in weak, uneven stands. Rhizoctonia is more prevalent if the weather is cool and wet. These conditions slow plant emergence and favour the growth of the fungus. Quadris in-furrow is a good management tool to control Rhizoctonia.

Late blight (Phytophthora infestans)
This is the most devastating fungal disease of potatoes. Infected seed is an important source of inoculum. Try to reduce the risk of planting infected seed by inspecting seed lots carefully. Look for slightly sunken, purplish areas of variable size on the surface of tubers. A granular, reddish brown dry rot develops under the skin. CFIA allows seed lots with one per cent of late blight and Fusarium infection combined. If there is one per cent late blight infection, you will end up with approximately 150 infected plants per acre. Some of the seed will rot before emergence, but cutting infected seed will spread the disease to healthy tubers. If more than one per cent of late blight is detected in a seed shipment, it is advisable not to plant the seed.

The fungicide Reason is registered as a seed treatment for late blight. Curzate applied at 80 per cent plant emergence is recommended if the seed originated in an area where late blight was problem the previous season.

If the growing season is cool and wet, it is impossible to eradicate the disease no matter how good the spray program. In 2016, late blight did not develop in Ontario, but it was detected in some seed-production areas both in Canada and in the US. Thus, check carefully for late blight when your seed shipment arrives.

Soft Rot (Pectobacterium carotovorum subsp. carotovorum)
Bacterial sot rot can cause serious losses. If about one per cent of the tubers in a seed lot show visible rot, excessive bacterial seed-piece decay may develop. The rotted tissues are wet and cream to tan in colour with a soft, granular consistency. Rotted tissues are sharply delineated from healthy ones by a blackish border. Secondary bacteria invade infected tubers rapidly causing a fishy smell.

Healthy seed tubers may be infected during cutting, and infected tubers will rot rapidly once planted. There are no seed treatments to control soft rot.

The Old Blackleg (Pectobacterium atrosepticum)
Symptoms on tubers are sunken, circular, black, rotted lesions extending from the tuber stem end into the pith. Rotting tissue is cream-coloured, but darkens with time. In an advanced stage, the infected tissue turns greyish black, mushy and smelly. Blackleg is more common in cool, wet seasons with temperatures below 250 Celsius.

There is no seed treatment for blackleg. Grade out infected tubers and make sure you disinfest the seed cutter often to reduce the spread of the disease to healthy tubers.

The New Dickeya Blackleg (Dickeya dianthicola)
The symptoms of tubers infected with Dickeya are similar to those caused by the old blackleg. The only difference is that the rot is slimier.

Seed tubers infected with Dickeya may appear healthy when coming out of storages. Dickeya’s optimum temperature for development is above 250 Celsius. Tubers infected at harvest will not develop symptoms in seed storages.

When seed tubers with latent infection are planted in the spring, they will rot quickly when the soil temperature increases in June.

The new Dickeya blackleg is much more aggressive than the old blackleg, and tubers are not often invaded by the secondary bacteria that cause rotting tubers to smell fishy. Thus, Dickeya infected tubers are usually odorless.

A specific, DNA-based test is necessary to distinguish Dickeya from the old blackleg. A & L laboratories in London, Ont., conducts PCR tests to identify Dickeya dianthicola.

It bears repeating that disinfesting seed cutters often reduces the spread of the pathogens that cause seed piece decay. An ounce of prevention is worth a pound of cure. Plant healthy seed.
Published in Vegetables
April 10, 2017, Calgary, Alta – An exclusive new Canadian distribution agreement between bio-ferm and Nufarm Agriculture Inc. adds two biological fungicides to Nufarm’s horticultural line of crop protection solutions.

Blossom Protect and Botector are now available from Nufarm in Canada, as part of the company’s lineup of herbicides, fungicides and insecticides for Canadian horticultural growers.

“Biological fungicides make up an important and growing part of our fungicide portfolio,” says Maria Dombrowsky, horticultural specialist at Nufarm Agriculture Inc. “Blossom Protect and Botector are great complements to our existing products, and will allow Nufarm to continue to support growers and their IPM programs.”

Blossom Protect is a biological fungicide that provides protection for pome fruit against fire blight (Erwinia amylovora). Botector is a biological fungicide used to protect grapes from botrytis (Botrytis cinerea).

bio-ferm products contain a unique mode of action that hinders the development of resistance,” says Werner Fischer, managing director with bio-ferm. “Our products are suitable for conventional and organic production, and bring the additional benefit of being safe for humans, animals and beneficials. They are certified through Ecocert Canada.”

Blossom Protect and Botector are available exclusively through Nufarm Agriculture Inc., its distributors and retailer partners across Canada.
Published in Diseases
April 3, 2017, Guelph, Ont – Syngenta Canada recently launched Aprovia Top fungicide, a new tool for controlling foliar early blight and suppressing brown spot.

Early blight, which is caused by the Alternaria solani fungus, is found in most potato growing regions. Foliar symptoms include small, brown, irregular or circular-shaped lesions that form on the potato plant’s lower leaves later in the season. The disease prefers warm, dry conditions to develop, and can be more severe in plants that are stressed and weakened.

Brown spot, caused by the Alternaria alternata fungus, is closely related to early blight and is found wherever potatoes are grown. Unlike early blight, brown spot can occur at any point during the growing season, producing small, dark brown lesions on the leaf surface.

Aprovia Top fungicide combines two modes of action with preventative and early curative activity on these two key diseases. Difenoconazole (Group 3) is absorbed by the leaf and moves from one side of the leaf to the other to protect both surfaces against disease. Solatenol (Group 7 SDHI) binds tightly to the leaf’s waxy layer and is gradually absorbed into the leaf tissue to provide residual protection.

“After a strong start, a foliar application of Aprovia Top can be used to manage these key diseases and keep potato crops greener longer,” says Eric Phillips, fungicides and insecticides product lead with Syngenta Canada.

Aprovia Top is available now for use in 2017 production. In potatoes, one case will treat up to 40 acres.

At this time, maximum residue limits (MRLs) for Solatenol use on potatoes have been established for markets in Canada and the U.S. Growers should consult with their processor prior to use.

In addition to potatoes, Aprovia Top can be used to control scab and powdery mildew in apples. Aprovia Top also provides control of early blight, powdery mildew, and Septoria leaf spot in fruiting vegetables, as well as powdery mildew, Alternaria blight and leaf spot in cucurbit vegetables.

See the Aprovia Top label for a complete list of crops and diseases.

For more information about Aprovia Top fungicide, please visit Syngenta.ca or the Customer Interaction Centre at 1‑87‑SYNGENTA (1‑877‑964‑3682).
Published in Diseases
March 28, 2017, Calgary, Alta – Four new crops have been added to the Presidio fungicide label as the result of Pest Management Regulatory Agency (PMRA) minor use approvals.

Presidio is now approved for use on ginseng, tobacco, brassica leafy vegetables and greenhouse ornamentals for a variety of troublesome diseases. The PMRA has also approved Presidio for control of pink rot on potatoes.

“These Presidio label additions are really important news for Canadian growers that depend on minor use approvals to protect their high value crops,” says Maria Dombrowsky, horticultural specialist at Nufarm Agriculture Inc. “Now more growers can access Presidio as part of their integrated pest management (IPM) program with a unique class of chemistry for better resistance management.”

Presidio (Group 43) provides growers with preventive and some curative reach-back action against downy mildew and Phytophthora spp., including late blight, on a variety of crops. In addition to these new crops, Presidio is also registered for use on head, stem and root brassica, cucurbits, fruiting vegetables and leafy vegetables.

“Presidio offers a great new option for domestic potato growers managing pink rot,” says Dombrowsky. “Growers should check with their processors before using Presidio on potatoes, because maximum residue limits (MRLs) for potatoes have not been established in all export markets.”
Published in Diseases
March 27, 2017, Guelph, Ont – Engage Agro Corporation has announced the release of two new products to serve horticultural producers across Canada.

Property 300 SC fungicide is a suspension concentrate fungicide that offers protection against powdery mildew in grapes, cucumbers, pumpkin, squash and melons.

Pyriofenone, the active ingredient in Property, is the newest generation chemical found in the FRAC U8 group. It demonstrates extremely fast translaminar activity that is complemented by a “vapour effect” that is stronger and longer lasting than that of other chemistries found in the same group.

Property is the only group U8 fungicide that can be applied up to the day of harvest on grapes.

Cosavet DF is a dry flowable sulphur fungicide that prevents powdery mildew and controls erinium mite of grape. Its patented formulation ensures a low dust, easy to mix product that helps to minimize the risk of scorching. Cosavet DF also controls a wide variety of diseases in tree fruit, Saskatooon berries, cucumbers and peas.

Variations in particle size ensure immediate, mid-term and residual activity through contact and vapour action to protect against target fungi.

For more information contact Engage Agro at This e-mail address is being protected from spambots. You need JavaScript enabled to view it or 1-866-613-3336.
Published in Diseases
March 27, 2017, Ridgetown, Ont – The Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) has released its 2017 schedule for integrated pest management (IPM) workshops for those who will be scouting horticultural crops this year. To register, please contact OMAFRA’s Agricultural Information Contact Centre at 1-877-424-1300.

Planning is also underway for scout training workshops for hops, hazelnuts and berry crops. Details for these workshops will be available soon.          

Introduction to IPM
May 2, 8:30 a.m. to 3:30 p.m.
Conference Rm 1, 2 and 3, 1st Floor, 1 Stone Rd. West, Guelph
Workshop Leader: Denise Beaton
Notes: Lunch on your own. Handouts provided. Pay parking ($12/day).
 
Tomatoes & Peppers
April 28, 8:30 a.m. to 1 p.m.          
Room 126 (Main Floor), Agronomy Building, University of Guelph, Ridgetown Campus
Workshop Leader: Janice LeBoeuf
Notes: Lunch on your own. Handouts provided. See Resources for Vegetable Crop Scouts.

Asparagus    
Field sessions available upon request
Email: Elaine Roddy, Vegetable Specialist – This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Cole Crops    
May 8, Time: TBD
Conference Rm 2, 1st Floor, 1 Stone Rd. West, Guelph
Workshop Leader: Dennis Van Dyk
Notes: Lunch on your own. Handouts provided. Pay parking ($12/day). See Resources for Vegetable Crop Scouts.

Lettuce, Celery, Onions, Carrots    
May 10, Time: TBD
Conference Rm 2, 1st Floor, 1 Stone Rd. West, Guelph
Workshop Leader: Dennis Van Dyk
Notes: Lunch on your own. Handouts provided. Pay parking ($12/day). See Resources for Vegetable Crop Scouts.

Sweet Corn, Bean and Pea
May 11, 9:30 a.m. to noon
Room 126 (Main Floor), Agronomy Building, University of Guelph, Ridgetown Campus
Workshop Leader: Elaine Roddy
Notes: Lunch on your own

Cucurbit Crops
May 11, 1 p.m. to 3:30 p.m.
Room 126 (Main Floor), Agronomy Building, University of Guelph, Ridgetown Campus
Workshop Leader: Elaine Roddy
Notes: Lunch on your own

Apples
May 4, 9 a.m. to 3 p.m.
Auditorium, Simcoe OMAFRA Resource Centre
Workshop Leader: Kristy Grigg-McGuffin
Notes: Lunch on your own. Handouts provided. If possible, bring OMAFRA Publications 360 & 310 (available for purchase as well).

Tender Fruit and Grape      
May 9, 9 a.m. to 1 p.m.
Rittenhouse Hall, Vineland OMAFRA Resource Centre
Workshop Leader: Wendy McFadden- Smith
Notes: Bring a laptop with WiFi capability. Lunch on your own.

Ginseng (IN-FIELD)  
June 15, 1 p.m. to 3:30 p.m. (Rain date: June 16, 1 p.m. – 3:30 p.m.)
C&R Atkinson Farms Ltd., 228 Charlotteville Rd. 1, St. Williams
Workshop Leaders: Sean Westerveld and Melanie Filotas

Published in Vegetables
February 7, 2017, Presque Ilse, ME – Potato seed tubers harboring Dickeya dianthicola and Pectobacterium wasabiae are the only confirmed source of these pathogens.

At this point, there is no evidence that either of the two pathogens overwinter in the soil. The generally accepted length of survival time in the soil for these pathogens is one week to six months, climate dependent. Longer survival is possible on plant matter in the soil. With that, the source of the inoculum, and hence the source of the disease, is seed. Therefore, any best management practices efforts on Dickeya dianthicola or Pectobacterium wasabiae must start with the seed.

Select seed from farms where Dickeya dianthicola or Pectobacterium wasabiae have not been detected and seed marketed in previous years has not been associated with Dickeya dianthicola or Pectobacterium wasabiae.

Check North American Certified Seed Potato Health Certificates before purchasing seed and select seed that had not been increased on a farm associated with Dickeya dianthicola or Pectobacterium wasabiae.

Select seed with zero blackleg levels reported on the North American Certified Seed Potato Health Certificate.
 
Select seed that has been PCR tested by an independent laboratory and confirmed to be free of Dickeya dianthicola and Pectobacterium wasabiae.

Select seed from farms where a zero tolerance approach to Dickeya dianthicola and Pectobacterium wasabiae is being implemented.

Seed lots with field readings of blackleg present should have reports that suspect plant samples were taken for testing and found to be Dickeya dianthicola and Pectobacterium wasabiae free.

Avoid seed from fields where symptoms of Dickeya dianthicola or Pectobacterium wasabiae were observed, even if affected plants were rogued out.

Where possible, avoid irrigated seed crops.

Where possible, avoid planting whole-seed lots that were stripped from multiple lots.
Published in Research
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