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
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.
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.
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.
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.