Coffee is the only known host of the fungus Hemileia vastatrix, which causes coffee rust also known as “roya”. The disease damages coffee leaves by causing the premature drop of infected leaves, which can lower yields by 50%.Coffee rust has become a greater problem for coffee growers because of climate change. Higher temperatures and increased rainfall favors rapid development of the disease.
“Costa Rica on Tuesday declared an emergency to tackle the spread of a coffee fungus that has already devastated Central American producers and looks set to destroy about 12 percent of Costa Rica’s planted coffee in the upcoming 2013/14 harvest.
A two-year emergency bill, signed jointly by Costa Rica’s Vice President Luis Liberman and the national coffee institute ICAFE, provisions about $4 million to pay for fungicides to tackle the roya, or leaf rust, outbreak.
Roya kills coffee leaves by sapping them of nutrients and lowering bean yields. The current roya pandemic has already affected other countries in Central America and Mexico, home to more than a fifth of the world’s Arabica coffee production.”
Author: Cota, I.
Affiliation: Reporter, Reuters.
Title: Costa Rica declares national emergency to tackle coffee fungus.
Source: Reuters. January 22, 2013.
Alternaria Brown Spot
Spain is a major producer of fresh oranges which are consumed throughout Europe. Disease infections in the citrus orchards can result in spots on the orange peel with no damage to the fruit inside. However, consumers will not pay top price for spotted oranges making fungicide use necessary.
“Alternaria brown spot (ABS) is a severe fungal disease of some mandarins and their hybrids in rainy and semiarid citrus-growing areas. … The presence of ABS in Spain has become a serious problem for ‘Fortune’ mandarin production.”
“Defoliation due to spring infections weakens trees and has an important impact on yield. However, fruit damage causes the most important economic losses. Fruit symptoms include light brown, slightly depressed spots to circular and dark brown areas on the external surface.”
“Although cultural practices that improve ventilation and prevent the growth of lush foliage can greatly reduce disease severity in the orchard, fungicide applications are essential to produce quality fruit for the fresh market. One or two sprays generally are needed to protect spring flush foliage to reduce defoliation and prevent inoculum build-up.”
Authors: A. Vicent, J. Armengol and J. García-Jiménez
Affiliation: Instituto Agroforestal Mediterráneo, Universidad Politécnica de Valencia, Valencia, Spain
Title: Rain fastness and persistence of fungicides for control of Alternaria brown spot of citrus.
Publication: Plant Disease. 2007. 91(4):393-399.
Mango – Anthracnose
Commonly known as the “King of Fruits,” the mango is the most important fruit of Asia. It is grown throughout the tropics and subtropics. Until recently, mango fruit was considered an exotic, specialty item in import markets such as the U.S. and Europe. Today a million tons of mangoes are exported. Among the diseases of mango, anthracnose is the most prevalent in humid growing regions. The incidence of this disease can reach almost 100% in fruit produced under wet or very humid conditions.
“Diseases are primary constraints to production in virtually all areas where mango is grown. … In humid regions, anthracnose is most destructive. … Pesticides are used in most commercial production situations, especially where anthracnose [is] important.”
“…irregular, dark brown to black lesions develop that are somewhat depressed and can crack the fruit surface. Under humid conditions, large areas may be involved and orange to pinkish masses of conidia are formed on the decaying surface. … Lesions on fruit are initially superficial, and penetrate deeper than 5 mm into the flesh only late in development. Anthracnose is caused by three closely related fungi. … Although some mango cultivars are moderately tolerant, none are sufficiently resistant to be produced without fungicides in humid areas.”
“In general, mango production currently has a heavy dependence on chemical disease control measures, especially where disease-conducive environments exist and when export quality fruit are desired.”
Author: R.C. Ploetz
University of Florida Tropical Research and Education Center, Homestead, FL
Title: The major diseases of mango: strategies and potential for sustainable management.
Publication: Proceedings of the VIIth International Symposium on Mango. 2004. 137-150.
Late Blight Tomatoes
The late blight fungus infects both tomatoes and potatoes. The fungus attacks all the aboveground parts of the plant. Infected foliage becomes brown, shrivels, and soon dies. When severe, all the plants in a field may be killed in a week. On tomato fruit, greenish brown greasy spots develop and can cover the entire tomato. Decaying vines can be identified by a foul odor. Environmental conditions in Brazil are ideal for the development of the disease.
“Tomato and potato are the most important vegetable crops in Brazil. During 2002, production of tomato and potato in Brazil totaled 3.6 and 3.1 million tons, respectively. The major producing areas are the south and southeast regions, in which 57.2% of the tomato and 92.3% of the potato are produced. Late blight, caused by Phytophthora infestans, occurs in both regions and is the most serious foliar disease of these crops. The environmental conditions in these regions also are highly favorable to late blight development, leading to severe crop losses if no control measures are adopted.”
“Due to favorable environmental conditions and high susceptibility to late blight, up to 20 and 15 fungicide sprays commonly are used in tomato and potato crops, respectively.”
Authors: A. Reis, F.H.S. Ribeiro, L.A. Maffia and E.S.G. Mizubuti
Affiliation: Departamento de Fitopatologia, Universidade Federal de Viçosa, Viçosa-MG, Brazil
Title: Sensitivity of Brazilian isolates of Phytophthora infestans to commonly used fungicides in tomato and potato crops.
Publication: Plant Disease. 2005. 89(12):1279-1284.
Apple scab is the most economically important disease of apples in the world. Fungal scab infections cause cracks in apples. Infected leaves fall off the tree which can result in reduced tree growth for one to three years. Apple growers worldwide have been spraying fungicides for over 100 years to control scab. And in New Zealand…..
“New Zealand apple industry spray programmes for control of black spot (scab), caused by Venturia inaequalis, typically use 16-20 fungicide applications each season, including dodine and fungicides in the demethylation inhibitor (DMI) group. These fungicides are particularly important to orchardists because their systemic activity prevents black spot development when they are applied after infection has occurred.”
Authors: R.M. Beresford1, P.J. Wright2, P.N. Wood3 and N.M. Park3
Affiliation: 1The New Zealand Institute for Plant & Food Research, Auckland, New Zealand; 2The New Zealand Institute for Plant & Food Research, Pukekohe, New Zealand; 3The New Zealand Institute for Plant & Food Research, Hawke’s Bay Centre, Hastings, New Zealand.
Title: Sensitivity of Venturia inaequalis to myclobutanil, penconazole and dodine in relation to fungicide use in Hawke’s Bay apple orchard.
Publication: New Zealand Plant Protection. 2012. 65:106-113.