Clubroot is a serious disease of crucifers. It is found in many countries across the world (see the Plantwise distribution map). It is caused by the fungus Plasmodiophora brassicae, whose spores can live for many years in the soil. This makes the disease difficult to control once a field has been infected.
To find out more about clubroot of crucifers and its management, read this month’s Plantwise Factsheet for Farmers which was written by staff from the Regional Agriculture Research & Development Centre in Sri Lanka. This factsheet is also available in Tamil and Sinhalese.
Guatemala has declared a state of agricultural emergency after coffee rust fungus has affected approximately 193,000ha of coffee, equating to 70% of the national crop. As a result of the outbreak, Guatemala is releasing $13.7m (£8.7m) in emergency aid to help farmers buy pesticides and to inform farmers on ways to manage the disease. Honduras and Costa Rica have already declared national emergency and El Salvador and Panama are also affected.
Coffee is a major export crop in many Central American countries and it is thought that this disease outbreak, which has been called “the worst seen in Central America and Mexico” by John Vandermeer, ecologist at the University of Michigan, will lead to big job losses. The Institute of Coffee in Costa Rica has estimated that the latest coffee rust outbreak may reduce the 2013-2014 harvest by 50% or more in the worst affected areas.
Cocoa, Theobroma cacao L. is the third most important export product in Ecuador; a country which produces 70% of the world’s highly prized Arriba cocoa. However, the sustainability of this crop is threatened by a number of devastating pest species including fungal diseases and insect pests. Among the most severe are the closely related fungal diseases Witches’ Broom Disease Moniliophthora perniciosa and Frosty Pod Rot Moniliophthora roreri, both of which occur in Ecuador. Frosty Pod Rot is an invasive disease which was originally identified in Ecuador in 1917 and has since spread rapidly to other Latin American countries. The fungal pathogen that causes Witches’ Broom Disease is a close relative of Frosty Pod Rot in the same Moniliophthora genus. In addition to the Moniliophthora diseases, Phytophthora spp. can lead to Black Rot of cocoa.These fungal diseases are a principle constraint on world cocoa production and affect the pods, flowers, leaves and stems, causing a decline in production and reduction in bean quality with infested plantations suffering dramatic yield losses and in some cases total loss of production. Breeding for disease resistance in cocoa is a key factor in maintaining sustainability of cocoa, since there is widespread concern over fungicide resistance, the safety and effectiveness of widespread pesticide use and recent tightening of regulations regarding pesticide residues on cocoa. The INIAP, national research institute of Ecuador, in collaboration with Mars Chocolate and the USDA is investing in substantial cocoa breeding programs with the aim of developing more productive, disease resistant, high yielding cocoa plants for Ecuadorian cocoa farmers. Continue reading →
Scientists have recently identified the first specimens of the fungus Sclerotinia subarctica in the UK. The fungus has not previously been found this far south and may pose a risk to UK agriculture. The findings were made by scientists at the Warwick Crop Centre at the University of Warwick. Continue reading →
In terms of food security the big story recently is that two regions of southern Somalia are in the midst of a famine. More than 10 million people are currently at risk of starvation with 1.8 million people displaced in East Africa’s worst drought for 60 years. Ethiopia and Kenya are neighbouring food insecure populations according to the UN food security classification.
However East Africa may soon experience more food shortages in the future due to yellow rust. Yellow rust (Puccinia striiformis) is a fungal disease which reduces wheat yields and can be found in many countries (Where is yellow rust found?). It causes the formation of necrotic areas and yellow pustules which together form stripes on the leaves. In the past it has not been found to destroy entire crops and was managed by the introduction of yellow rust resistant varieties in the 1970s. Recently a more aggressive strain of yellow rust has appeared and has already affected parts of Europe, Australia and the US. It is able to generate more spores than previous strains and spread more rapidly.
The international community had largely ignored this new strain in its fight against another wheat disease. Ug99 is a strain of stem rust (Puccinia graminis) which was first detected in 1998 and is traditionally regarded as more of a threat than yellow rust in the areas that it exists in (Where is stem rust found?). However this new strain of yellow rust is now considered more of a threat to wheat yields.
Changes in the climate can have dire consequences for farmers within developing countries. They can change the distribution ranges of insect pests, causing pests to migrate into new areas which are not prepared for them. Farmers may not have the knowledge to identify these new insect pests and take appropriate action to reduce the harm that they can cause to their crops.
As part of the Plantwise initiative CABI is increasing support to farmers face-to-face via a network of plant clinics in the developing world and also via a comprehensive global knowledge bank. Specially trained ‘plant doctors’ help farmers identify problems affecting their crops. Advice and treatment recommendations are offered along with information on the disease in local languages in the form of factsheets, leaflets and posters, an example being Coffee wilt disease.
A mysterious disease is blighting Afghan opium poppy (Papaver somniferum) destroying nearly half of the opium harvest in 2010, according to a report published in September by the UN Office on Drugs and Crime. Production in 2010 was at its lowest level since 2003, estimated at 3,600 tonnes – a 48% decrease from 6,900 tonnes in 2009. Reduced harvests could boost profits for insurgent groups such as the Taliban and fuel their propaganda war against US troops, but it may also provide an opportunity to persuade Afghan farmers to focus on growing alternative crops.