Experts shed light on pink eye disease of potatoes

Image result for pink eye disease potatoPink eye is a disorder of potato tubers that can cause costly storage losses for potato growers and can reduce tuber quality to the point where tubers will be rejected by potato processors. Pink eye not only directly affects tubers, but also makes tubers more susceptible to diseases such as Pythium leak, bacterial soft rot, pink rot, and Fusarium dry rot. These diseases cause additional storage losses and reduction in quality. According to scientists Yi Wang, UW-Horticulture and Amanda Gevens, UW-Madison Plant Pathology in the US, pink eye is characterized by a short-lived external pink color that is often, but not always, found around the potato eyes of freshly harvested tubers. Eyes at the bud ends of tubers (i.e., those farthest from where tubers are attached to stems) more commonly show pink eye symptoms. The scientists say pink eye can eventually develop into corky patch/bull hide, which involves a thickening of areas of tuber skin extending approximately 1/10 of an inch into the tuber flesh. Read more

Potato virus found for first time in New Zealand

Image result for potato mop-top virusA damaging potato crop virus could have a serious impact on the potato industry if not contained, an expert says. The potato mop-top virus (PMTV) has been discovered in New Zealand for the first time on two farms in Canterbury on the South Island. The virus causes a defect in the potato that means it can’t be processed for potato chips and oven fries, but does not pose a health risk. Affected potatoes can display symptoms including distortions to the skin, deep cracking, and rust-coloured arcs, streaks or flecks in the tuber flesh. Potatoes New Zealand chief executive Chris Claridge said they were investigating to see where the virus had come from and if it had spread to any other potato crops in the country. “It is so important for us to isolate and contain the virus and, if possible, eradicate it,” he said. Read more

Late blight expert: ‘How do you disarm Phytophthora?’

Plant breeders regularly claim to have developed a new potato variety that is resistant to the harmful micro-organism Phytophthora infestans (see inset). By cross-breeding they have introduced a resistance gene that they think will keep the little fungus-like pathogen out. But Francine Govers, professor in Phytopathology and a leading expert on Phytophthora, never makes these kinds of claims. She knows that the stubborn pathogen cannot be stopped with a single resistance gene and will get around this new defence barrier sooner or later. So, Wageningen University and Research (WUR) in the Netherlands is looking for heavier weaponry with which to protect potatoes from Phytophthora infection. Firstly, Govers and colleagues at the Laboratory for Plant Breeding are looking into how they can bolster the potato’s defences using new techniques. Secondly, they are looking at how they can deactivate Phytophthora’s weapons, the so-called effectors. Read more

Late blight update issued for the UK

Image result for fight against blight ahdbAccording to Dr James Cooke at the James Hutton Institute in Scotland, having experienced one of the driest seasons since the Fight Against Blight began – clearly the weather has had a major impact. “After some early appearances on discard piles in Kent in mid-April, we have received very few recorded outbreaks compared to previous years. This has allowed us the time to genotype the samples as they arrived in the lab, and we now have genotype data for 24 positive outbreaks.” The data indicates a similar pattern to last year with the new lineages 37_A2 and 36_A2 in Kent and, more recently, in Shropshire. There have been no findings of these genotypes beyond their 2017 range but the hot, dry weather will have been a major factor in limiting pathogen movement. There are only two confirmed outbreaks from Lincolnshire, to date, so there remains a possibility that it is present but not yet sampled. Read full update on the AHDB Potatoes website

How to manage pink rot in potatoes

potato-pink-rotThis pathogen thrives in saturated soils, so the disease is often associated with low spots in the field or in areas of poor drainage. Disease incidence is greatest at temperatures between 70°F and 85°F. You may not notice pink rot until harvest or when the tubers are in storage, but it starts in the field. Infections often originate at the stolon attachment but also may occur at the eyes or through wounds. There are several tell-tale indicators of pink rot, says Carrie Huffman Wohelb, Associate Professor/Regional Specialist – Potato, Vegetable, and Seed Crops, at Washington State University. According to her, the most frequently used oomycete fungicides for managing pink rot in the US are mefenoxam (e.g., Syngenta’s Ridomil Gold, Nufarm’s Ultra Flourish) and metalaxyl (e.g., LG Life Sciences’ MetaStar). Mefenoxam is also known as metalaxyl-M and is chemically similar to metalaxyl. Wohelb warns that growers should be aware of resistance issues. Read more

After first assault, zebra chip still a dangerous foe in the US

When zebra chip burst onto the scene in the U.S. in the 2000s, it came as a nasty surprise for many growers and cost producers millions of dollars. A little over a decade later, is zebra chip still as serious of a threat as it was then, and do researchers have a better handle on how the disease works and how to fight it? The answer to the first of those questions, is an emphatic yes according to Charlie Rush who directs the research program in plant pathology at Texas A&M AgriLife Research in Amarillo. “There is no question it is still potentially devastating,” he said. “They (growers) get where they have a low-pressure year and they stop worrying about it or they use their chemicals wisely and have good control for a few years and they start thinking it’s not really out there anymore, it’s not a problem, I can back off, and that’s when they get hurt.” To answer the second question, researchers have made advances in knowing more about how the disease is spread by its vector, the potato psyllid, and how the disease manifests. Read more

US scientists identified new mefenoxam resistant late blight strain

Image result for potato late blightAccording to Amanda J. Gevens, Associate Professor & Extension Vegetable Plant Pathologist at the Dept. of Plant Pathology, UW-Madison, a new late blight strain type, US-25 has recently been identified in New York State. According to Prof Gevens, this strain has, to this point, been found only on tomato. In a weekly newsletter, she says that Dr. Christine Smart, Professor at Cornell University, has been keeping extension and research pathologists informed of this new type, which is now known to be mefenoxam resistant and of the A2 mating type. Prof Smart reported that under lab conditions, US-25 will infect potato as well as tomato. Prof Gevens further says that “all samples tested from the Great Lakes region, USA region including WI, IL, and MI to date, have been US-23. The MN tomato late blight finding from several weeks back was not genotyped.” Continue reading

Nemathorin: Online calculator assists British growers with date check for potato harvest interval

Nemathorin Harvest Interval CalculatorPotato maincrop harvesting is set to get underway in Britain, following a season of extreme heat and drought. Where establishment was significantly delayed, growers are being reminded to check the pre-harvest interval from the date of planting, to desiccation and lifting, advocates Syngenta Potato Technical Manager, Michael Tait. After the use of Nemathorin, there is a 17 week (119 day) minimum interval from application to desiccation or green-top lifting. “It is essential that growers check and record the harvest interval, to ensure they fulfill the requirement,” says Michael. This year, many growers could leave crops for longer to bulk up, after slow development in hot dry conditions. That could extend their time in the ground beyond the PHI, Michael added.  Continue reading

PVY-resistant GMO potato variety approved by Argentine authorities

La licencia de uso del evento será de la firma Tecnoplant (subsidiaria del grupo Sidus).Argentine authorities have officially approved the commercialization of a genetically modified PVY-resistant potato variety. The transgenic potato, named TIC-AR233-5, will help growers avoid losses from the virus. The virus can result in yield declines of up to 70%, according to Argentina-based Tecnoplant, which holds the marketing license. The potato will also help growers to use fewer agrochemicals in its cultivation, the company said. The Health and Agri-Food Quality National Service, Senasa, said the product complies with all the necessary requirements, according to La Nación. According to Andrés Murchison, Secretary for Food and Bioeconomy, the new potato could help growers to reduce handling costs and could also boost the quality of the final product. It is expected that regulatory processes for other GMO crops will continue to be optimized in the future, said Murchinson. Read more. Report by Technoplant in Spanish.

Canadian farmers caught up in fight over chemicals

It’s fair to say that Canadian farmers are feeling a little shell-shocked after not one, but two, decisions in the space of one week that could fundamentally change their access to chemical control. First was the California jury’s decision to award US$289 million to a man dying of cancer after deciding his exposure to the commonly used herbicide glyphosate contributed to his condition and that product labels did not adequately warn him of the risk. The second was a decision announced this week by the Pest Management Regulatory Agency, a division of Health Canada, to phase out neonicotinoids, a class of insecticides widely used in canola, corn, soybeans and horticultural crops. These insecticides first came under scrutiny because of their link to unusually high losses of bees and other pollinators. But it is their impact on aquatic insects that are critical food sources to fish, birds and other animals that led to the decisions announced this week. Reaction from the Canadian farm community is a mix of incredulity and outrage. Read more

Tobacco rattle virus in potato explained

Photo, S.K.R. Yellareddygari, NDSUCorky ring spot is becoming more economically important across several potato production regions in the U.S. largely due to the spread of tobacco rattle virus (TRV) and because of restrictions on the use of current chemical control options. Potato specialists at NDSU/University of Minnesota recently published a factsheet explaining the influence of TRV on potato production. They note that tobacco rattle virus incidence has been reported in potato production areas in California, Colorado, Florida, Idaho, Michigan, Minnesota, North Dakota, Oregon, Washington and Wisconsin. The virus has a broad host range, including potato, tobacco, corn, barley, sunflower, ornamental (tulip, iris, etc.) and a variety of weed hosts. The virus is transmitted in the field by soil-inhabiting stubby root nematodes of the genera Trichodorus and Paratrichodorus. Nematicides, soil fumigation and resistant cultivars can be used for nematode management. Detecting and quantifying viruliferous nematodes is important for making planting decisions and management approaches. Read more

Heavy rain, humid conditions and threat of potato blight forecast for Ireland

Weather outlook: Heavy rain, humid conditions and threat of potato blight forecastUnsettled weather conditions are in store this week for Ireland with a mixture of sunny spells, heavy rain, rising temperatures and humid conditions expected countrywide, according to Met Eireann. The national meteorological service has reiterated its Status Yellow warning that current conditions are conducive to the spread of potato blight – which it expects is “likely to develop” in parts of west Ulster later today (August 14). In its latest farming commentary, Met Eireann said it is likely that a spell of rain on Wednesday (August 15) will bring “significant rainfall amounts” to all parts of the country resulting in above average rainfall amounts. It is anticipated that the rain will extend eastwards throughout the day bringing a “steady fall” of rain across the country. The rain will clear to showers on Wednesday evening. Highest temperatures are due to reach between 17° and 21° early in the day – with moderate to fresh southerly winds veering southwesterly with the clearing rain and introducing cooler, fresher conditions. Read more

The glyphosate saga: $289 million Roundup cancer verdict sends Bayer shares reeling

Roundup products are seen for sale at a hardware store in San Rafael, California, on July, 9, 2018Bayer shares plunged on Monday, losing about $14 billion in value, after newly acquired Monsanto was ordered to pay $289 million in damages in the first of possibly thousands of U.S. lawsuits over alleged links between a weedkiller and cancer. After the verdict in favor of a California school groundskeeper with terminal cancer, Monsanto faces more than 5,000 similar lawsuits across the United States over claims it did not warn of the cancer risks of glyphosate-based weedkillers, including its Roundup brand. But the US Environmental Protection Agency (EPA) continues to insist that glyphosate is safe when used carefully. Bayer shares were down 11.2 percent, the worst performing stock on the Stoxx Europe 600 index, and on track to close at their lowest in almost five years. Barclays analysts said Bayer was in for a “litigious headache”.  Continue reading

Plants use calcium to send internal warning of attacking aphids

Scientists at the John Innes Centre have discovered how plants send internal warning signals in response to an attack by aphids. They found that when the insect feeds on a leaf it triggers the plant to admit calcium into the damaged cells. This small flux of calcium prompts the plant to signal that an attack is underway, and a larger amount of calcium is then mobilized from within the cell. These discoveries were the result of a collaboration between Professors Saskia Hogenhout and Dale Sanders. Professor Sanders elaborates on the findings: “We now know that when an aphid feeds on a leaf, the plant uses calcium as a warning signal. This signal forms part of the plant’s defense mechanism.” Understanding how plants respond and ultimately defend themselves from an attack is important for identifying ways in which these pests can be managed. Read more

Blight: Integrated thinking for late blight control

Earlier this spring AHDB in the UK produced comprehensive new guidance on controlling late blight in light of the increase in the aggressive blight strain 37_A2. CPM takes a closer look. There’s been much talk about blight programmes since the 37_A2 late blight genotype emerged in the UK. It’s of particular significance because the new strain appears to be aggressive, highlighted by its relatively rapid increase in the blight population last season (from 3 to 24% of samples tested). As well as its ability to compete with rival blight strains, 37_A2 has a reduced sensitivity to fluazinam, which played a part in some of the problems experienced with tuber blight.  Continue reading