Tag Archives: disease

Phytophthora infestans identified early in tomato season

AHDB Horticulture has reported that symptoms of Phytopthora infestans causing late blight on tomato crops have been seen earlier than usual this year.

According to reports, symptoms seen on young plants included some leaf spotting and widespread stem lesions, usually starting just above the graft union. According to AHDB: ‘These early symptoms resulted in significant plant losses, though some plants survived while still exhibiting brown stem lesions.  Browning on stems is not deep and doesn’t appear to penetrate to level of the vascular tissues. The browning spreads right round and then along affected stems and bears a superficial resemblance to Botrytis stem rot, although generally stems of plants that have survived the initial stages of the disease do not wilt and die off like Botrytis-affected stems.’

A post on the levy board’s website also confirmed: ‘On one nursery assessed during May 2018, all symptomatic plants were exhibiting symptoms at a comparable stage with no visible evidence of secondary infection, although the browning was still extending at a rate of several cm per week. Immunodiagnostic tests were carried out to compare swab samples from plant surfaces and various surfaces within the greenhouse, with stem tissue scrapes and leaf samples. These tests showed strong presence of P. infestans in the brown lesions and no presence in any green tissues tested.  Two infected plants have been tested by The James Hutton Institute, who have identified them both as belonging to the EU 39 A1 genotype.’

Photo Caption: Early season infection has been characterised by stem lesions

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Lettuce Fusarium wilt confirmed at new sites

Following its confirmation as a new disease in October last year, Lettuce Fusarium wilt caused by Fusarium oxysporumf. sp. lactucae(FOL) has now been confirmed by laboratory analysis at two new sites in Lancashire, while a further outbreak is suspected at a site in Cambridgeshire.

All outbreaks confirmed to date have been caused by FOL race 4, which is also present in the Netherlands, Belgium and Ireland. For protected cropping, Basamid (dazomet) is approved for de-infestation of soil before planting (one application in every third year) and is known to have activity against lettuce FOL, but in open field situations a long period between crops is advised as the disease can survive in the soil for several years.

Plants with suspect leaf symptoms should be cut in half from top to bottom to check for red/brown staining in the root which is a characteristic symptom of Fusarium wilt. Samples can be sent to Dr John Carkson at Warwick University for testing.

Photo Caption: Lettuce growers are warned to be vigilant for signs for Lettuce Fusarium wilt.

Photo Credit: pxhere

The post Lettuce Fusarium wilt confirmed at new sites appeared first on Hort News on 6 September 2018.

Irish potato growers worried by threat of blight

After months of hot dry weather, Irish potato growers are now concerned that a break in the weather could create ideal conditions for late blight to infect stressed crops.

According to a report, unsettled weather is expected for a least a week across Ireland with a mixture of sunny spells, heavy rain, rising temperatures and humid conditions expected. The forecast caused national meteorological service Met Eireann to reiterate a 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 from 14 August.

The warning was first issues last Friday (10 August) and the forecaster also warned that, ‘Opportunities for both drying and spraying will be limited over the coming days’ which could create a perfect storm of conditions which favour disease development but prevent growers controlling its spread.

Photo Caption: Irish potato growers expect weather conditions to be ideal for the spread of potato late blight this week

Photo Credit: Wikipedia Commons

The post Irish potato growers worried by threat of blight appeared first on Hort News on 20 August 2018.

Drones could spot potato virus in fields

A US scientist is investigating the potential of using aerial drones or unmanned aerial vehicles (UAV) to spot symptoms of potato diseases live PVY.

Donna Delparte, assistant professor in the Department of Geosciences at Idaho State University (ISU) discussed her research at the Idaho Potato Conference in January.

“They are very much the future, especially when we’re working on trying to expand the technology and look at new and novel ways to use UAV, such as crop-invasive species,” she said.

Using a special camera it’s possible to fly a drone over a field and determine the precise locations of plants infected with PVY with a reasonable level of certainty. Delparte’s team created a profile of what an infected plant looks like with a hyperspectral camera, and then took that profile to the field to identify infected plants. The results were ‘ground-truthed’ and after tuning the algorithm reached an 89.8 percent success rate.

The drone imagery combined with a Real Time Kinematic (RTK) GPS system, provided the location of the PVY infected potato plants. “Imagine we send a farmer a dot on a map or a GPS that says, ‘this is where you should be able to find PVY infected plants,’ and be able to do some sort of mitigation,” Delparte explained.

Despite the promise, the costs of the camera and the computing power required to crunch the large amount of data generated are both issues which need to be overcome.

Photo Credit: pxhere

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PRGO to hold pea and bean crop protection course

PGRO will hold its next course on Pea & Bean Crop Protection at its will be held at its Research Station at Thornhaugh near Peterborough on 6 February 2018.

The one day course provides agronomists, consultants, growers and crop managers with the latest updates in crop protection for both vining and combining peas, as well as winter and spring field beans. Major pests, diseases, disorders and weed control strategies, will be covered with the aim that participants can correctly identify pests, diseases and disorders following the training. They will also appreciate the regional and national significance, be aware of herbicide options (including the strengths and weaknesses of different herbicides), and be able incorporate control measures into integrated pest management programmes.

The course is recognised by BASIS and costs £205.00 per person (including VAT). The fees cover lunch, refreshments and literature. Applications should be made by 30th January latest. Interested parties should contact Sue Bingham (sue@pgro.org) for booking details as numbers are strictly limited.

Photo Caption: The course covers all major pests and diseases of peas and beans.

Photo Credit: Wikimedia

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PGRO offers rapid clubroot test

PGRO is now offering commercial growers an early indication of clubroot risk to brassica crops including vegetables and oilseed rape.

“PGRO is offering a rapid molecular test for the detection and quantification of the brassica clubroot pathogen Plasmodiophora brassicae in the soil that can be used as a risk assessment tool by growers,” says Roger Vickers, PGRO’s Chief Executive. “The test is proving invaluable to close rotation intensive vegetable producers as well as to growers of oilseed rape – which is the most commonly grown brassica crop in the UK.

“Clubroot infection can cause significant, or even complete, crop losses when infection is severe, and is exacerbated by close rotations. Plasmodiophora brassicae can persist in soils for at least 15 years so cannot be managed practically by extending rotations.”

Dr Lea Herold, PGRO Plant Pathologist explains that the test, which was first launched last summer, determines the number of pathogen resting spores per gram of soil. “The higher the numbers of spores per gram soil the higher the risk of disease development,” she says. “Growers receive a risk indicator for their soil, with the level of risk defined on a 1-3 scale (slight, moderate or severe) according to infection levels identified as set out in AHDB Horticulture Project CP 099a.”

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Effective controls for apple canker identified

Two new fungicides have been identified for the control of apple canker, caused by the fungus Neonectria ditissima, while research into integrated pest management of the disease is also providing promising results.

Canker is one of the most important diseases of apple and pear, causing cankers and dieback of young shoots, as well as fruit rot that can result in losses as high as ten per cent or more in stored fruit. In a two-year AHDB Horticulture funded trial examining control of Neonectria fruit rot, a range of experimental fungicides, a biofungicide and several alternative chemical treatments were tested for effectiveness. During the trials, fungicides Delan Pro and Syllit 400SC were found to be effective at reducing the incidence of fruit rot.

A five-year IPM study, also commissioned by AHDB Horticulture, is looking at how apple canker spreads. The project aims to identify an approach to reduce losses during tree establishment by targeting infection at propagation phase and improving the efficacy of orchard control.

Mark Holden, from Adrian Scripps Ltd is an industry representative of the project. He commented, “Losses of trees due to canker have risen significantly over the last 10 years due to more intensive tree planting, particularly with more susceptible varieties such as Gala, Braeburn, Kanzi & Jazz.

“The main issue is the lack of systemic chemical products in the growing season which are effective so it is encouraging that some new chemistry is coming through. It is hoped that, after the registration process is completed for these new products, the label requirements are not too restrictive.”

Photo Caption: Neonectria ditissima

Photo Credit: Wikipedia Commons

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Composters warned of Xylella threat

To help protect EU Member States against the introduction of Xylella fastidiosa, EU emergency legislation has been introduced, which includes requirements to protect against introductions from non-EU countries, as well as from those parts of the EU where it is has been detected.

As well as introducing requirements for imports of non-EU plants and the movement of ‘specified plants’ (which include the confirmed hosts of Xylella fastidiosa in the EU and further afield), speaking at the annual Organics Recycling Group conference on 3 March, Mike Dennison, veterinary officer at the APHA said, “There is a new plant disease in the news. It is quite possible this could have an effect in terms of composting which needs to be controlled.” He suggested that this could mean composts from at risk sources needed to be heat treated, for example through In-Vessel Composting or anaerobic digestion.

Photo Caption: Dieback caused by Xylella

Photo Credit: Wikipedia

The post Composters warned of Xylella threat appeared first on Hort News on 17 March 2016.