Factsheet of the month: April – Wheat stem rust

wheat stem rustLast week, the Borlaug Summit on Wheat for Food Security took place in Mexico, bringing together thought leaders, policymakers, and leading agricultural research-for-development organizations to discuss the role of wheat in the future of food security. Wheat is an extremely important crop that provides around 20% of the world’s calories but this staple crop is threatened in some areas by a fungal disease called stem rust.

To find out about the symptoms and management of wheat stem rust, please click the Wheat stem rust factsheet which was produced in Rwanda (also available in Kinyarwandan).

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Update: New Pest & Disease Records (20 Mar 14)

Sclerotium rolfsii, causing leaf chlorosis, and root and collar rot of apple has been found in Tunisia © University of Georgia

Sclerotium rolfsii, causing leaf chlorosis, and root and collar rot of apple has been found in Tunisia © University of Georgia

We’ve selected a few of the latest new geographic, host and species records for plant pests and diseases from CAB Abstracts. Records this fortnight include the first report of a ‘Candidatus Phytoplasma Ziziphi’- related strain associated with peach decline disease in India, molecular and morphological characterisation of Scutellonema bradys from yam in Costa Rica and the first report of apple collar rot incited by Sclerotium rolfsii in Tunisia.

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Plantwise 2013 Highlights

PW collage

As we move into the New Year and all that 2014 has to offer it seems like a good time to review some of the achievements of 2013. Here are a few of the Plantwise highlights of 2013!

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Herbicide Resistance Gene In Black-Grass and Rye-Grass Identified

Black-grass (Alopecurus myosuroides), a serious weed of arable fields that is widley resistant to herbicides © Bas Kers, via Flickr (CC-BY-NC-SA 2.0)

Black-grass (Alopecurus myosuroides), a serious weed of arable fields that is widley resistant to herbicides © Bas Kers, via Flickr (CC-BY-NC-SA 2.0)

BBSRC (Biotechnology and Biological Sciences Research Council) and Syngenta funded scientists at the University of York and University of Durham have discovered a gene called AmGSTF1 that plays a key role in controlling multiple herbicide resistance in black-grass (Alopecurus myosuroides) and annual rye-grass (Lolium rigidum). Now the gene that confers resistance has been identified, it is hoped that chemicals that inhibit the gene may be able to be used in future to make herbicides effective against resistant weeds.

Black-grass and rye-grass are widespread weeds which cause problems in cereal and oilseed rape farming. Management using herbicides is becoming increasingly difficult since both black-grass and rye-grass can acquire a single defence mechanism that confers resistance to multiple herbicides- known as multiple herbicide resistance. The genetics of multiple herbicide resistance have been poorly understood until recently, however scientists have now discovered that a gene producing an enzyme called glutathione transferase (GST) is responsible for multiple herbicide resistance. Scientists created transgenic thale cress (Arabidopsis thaliana) plants with the GST producing gene inserted which were resistant. GSTs are known to detoxify herbicides, but project leader Professor Rob Edwards of the Centre for Novel Agricultural Products at the University of York believes that the gene they discovered works as a kind of ‘master switch’ that activates a range of protective mechanisms in the plant. When resistant plants with the GST gene are sprayed with GST inhibiting chemicals, they become susceptible to herbicides. This demonstrates the potential for using GST inhibiting compounds in future herbicide formulations to manage resistant rye-grass and black-grass. These weeds are currently very difficult to manage due to their widespread herbicide resistance.

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Black Rot Disease Hits Uganda

A photograph of a cabbage leaf showing symptoms of black rot. Image by USDA Forest Service via Wikimedia Commons (CC-BY 3.0)

A photograph of a cabbage leaf showing symptoms of black rot. Image by USDA Forest Service via Wikimedia Commons (CC-BY 3.0)

Vegetable farmers in the Kayunga and Mukono districts of Uganda are reporting crop losses due to black rot disease. One farmer, Twaha Kahooza of Kyampisi village, Kayunga Sub-county, says he had planted four acres of cabbages and was expecting about Shs18m (about £4,500 or US$7,000) from the harvest, however he only managed to get Shs5m (about £1,200 or US$2,000).

Black rot is caused by the bacterium Xanthomonas campestris pv. campestris and is one of the most destructive diseases of cabbage and other crucifers such as  broccoli, brussels sprouts, Chinese cabbage, collards, kohlrabi and mustard. The disease is usually most prevalent in low lying areas where plants remain wet for long periods. The disease is characterized by a yellow V-shaped lesion at the leaf margin which turns brown as the leaf area expands. The disease can also affect seedlings and can enter the plant through insect feeding or injury to the plant. Management of black rot in crucifers includes obtaining certified, pathogen free seed, ensuring there is enough space between plants and crop rotation.To read more about black rot and black rot management visit factsheets on the Plantwise Knowledge Bank.  

To read a Plantwise Factsheet for Farmers written in Uganda click here. 

To find out more about Plantwise plant clinics running in Uganda, click here

References:

‘Farmers count losses over black rot disease in cabbage’, Fred Muzaale, April 2013, Daily Monitor 

Maize Lethal Necrosis Disease Spreads To Uganda

Maize plants showing Maize Lethal Necrosis disease © CIMMYT via Flickr (License CC-BY-NC-SA 2.0)

Maize plants showing Maize Lethal Necrosis disease © CIMMYT via Flickr (License CC-BY-NC-SA 2.0)

Maize Lethal Necrosis disease, which was first reported in Kenya and Tanzania, has now spread to Uganda, raising concerns for food security in the country. The Ministry of Agriculture has warned that Maize Lethal Necrosis has been reported in districts in eastern Uganda, including Busia and Tororo.

A spokesman for the Agriculture Research Organisation, Robert Anguzo, has said that Ugandan scientists are working in collaboration with the International Maize and Wheat Improvement Centre (CIMMYT) to find management solutions to the disease.

More information about the pests and viruses associated with Maize Lethal Necrosis and the management of the disease can be found on the Plantwise Knowledge Bank

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Plantwise Photo Of The Month- April

Participants at the first Plant Health Rally to take place in Santa Cruz, Bolivia © CABI UK

Participants at the first Plant Health Rally to take place in Santa Cruz, Bolivia © CABI UK

To read more about the work Plantwise is doing in Bolivia follow this link. To read Spanish factsheets specific to Bolivia on the Plantwise Knowledge Bank click here.

Plantwise launches in Ghana

Workshop opening ceremony included words from (l-r): Dr Victor Clottey, Dr Entsua-Mensah, Dr Samuel Kojo Dapaah and Morris Akiri © CABI

Workshop opening ceremony included words from (l-r) Dr Victor Clottey, Dr Entsua-Mensah, Dr Samuel Kojo Dapaah and Morris Akiri © CABI

Plantwise, a global initiative run by CABI, was launched in Accra, Ghana last week. The initiative involves establishing plant clinics, which farmers can attend to get advice on plant health from trained plant doctors. In addition to the knowledge they acquire through the training programmes, these plant doctors can make use of the Plantwise Knowledge Bank which provides up-to-date information to best advise the farmer.

Following the launch, a review and planning workshop took place for stakeholders in the agricultural sector.  The event attracted policy makers, extension workers, plant protection officers and researchers as well as private sector and non-governmental agencies who were all keen to share their knowledge and ideas on how to develop Plantwise activities in the country. Read more of this post

Monitoring and Management of Desert Locusts in Africa

An adult Desert Locust © AtelierMonpli via Wikimedia Commons (License CC-BY-SA-3.0)

An adult Desert Locust © AtelierMonpli via Wikimedia Commons (License CC-BY-SA-3.0)

The United Nations Food and Agriculture Organisation (FAO) has this month warned that Desert Locust (Schistocerca gregaria) swarms are invading cropping areas of northern Sudan. The swarms originated from winter breeding areas on the Red Sea coastal plains and subcoastal areas in northeast Sudan and southeast Egypt. The situation requires close monitoring as more swarms are expected to form in the coming weeks that could move into parts of  Sudan and southern Egypt. If no further rains fall and the vegetation dries out, some of these swarms could move into the interior of both countries and also cross the Red Sea to the coast of Saudi Arabia.

Locusts belong to the Acrididae family (in the order Orthoptera which includes grasshoppers and crickets) and when triggered by certain cues such as increased crowding with other locusts have the ability to change their morphology, behaviour and physiology over several generations. This phase change occurs from a solitary to a gregarious phase, eventually causing the locusts to form dense hopper bands and swarms. One of the most serious locust pests is the Desert Locust.

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New Type of Invasive Whitefly Recorded In South Africa

The whitefly Bemisia tabaci (USDA image PD USDA ARS via Wikimedia Commons)

The whitefly Bemisia tabaci (USDA image PD USDA ARS via Wikimedia Commons)

A species of whitefly that transmits cassava mosaic virus has been detected in South Africa for the first time. The whitefly, Bemisia tabaci is a cryptic species complex containing some important agricultural pests and virus vectors. The term ‘cryptic species complex’ means that Bemisia tabaci is considered to be a complex of at least 24 different species that look almost identical but are in fact genetically different.  Researchers from a range of organisations including the University of Johannesburg, the University of Witwatersrand and ARC-Vegetable and Ornamental Plant Institute conducted surveys to investigate the diversity and distribution of Bemisia tabaci species in 8 provinces in South Africa. The study aimed to update the information regarding the different Bemisia tabaci types present in the country.

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