Weeds harbor Fusarium species that cause malformation disease of economically important trees in western Mexico

Mango malformation disease (MMD) caused by Fusarium spp. is an important limiting factor in most production areas worldwide. Fusarium mexicanum and F. pseudocircinatum have been reported as causing MMD in Mexico. These two pathogens also cause a similar disease in Swietenia macrophylla (big-leaf mahogany malformation disease or BLMMD) in central western Mexico, while F. pseudocircinatum was recently reported as causing malformation disease in Tabebuia rosea (rosy trumpet) in the same region. These studies suggest that additional plant species, including weeds, might be hosts of these pathogens. The role that weed hosts might have in the disease cycle is unknown. The objectives of this work were to recover Fusarium isolates from understory vegetation in mango orchards with MMD, identify the Fusarium isolates using DNA sequence data, and determine if F. mexicanum is capable of inducing disease in the weedy legume Senna uniflora (oneleaf senna). Additional objectives in this work were to compare Fusarium isolates recovered from weeds and mango trees in the same orchards, by characterizing their phylogenetic relationships, assessing in vitro production of mycotoxins, and identifying their mating type idiomorph. A total of 59 Fusarium isolates from five species complexes were recovered from apical and lateral buds from four weed species. Two of the species within the F. fujikuroi species complex are known to cause MMD in Mexico. Trichothecene production was detected in five isolates, including F. sulawense and F. irregulare in the F. incarnatum-equiseti species complex and F. boothii in the F. sambucinum species complex. Both mating types were present among mango and weed isolates. This is the first report of herbaceous hosts harboring Fusarium species that cause mango malformation in Mexico. The information provided should prove valuable for further study of the epidemiological role of weeds in MMD, and help manage the disease.

CHARACTERIZATION OF FUSARIUM SPECIES ASSOCIATED WITH MANGO MALFORMATION DISEASE IN SOUTHERN SENEGAL

In Senegal mango production has long existed in traditional forms, especially in the south and center of the country. It accounts for 60% of the countrys fruit production, with an estimated annual output of 150,000 tons. Despite a positive balance sheet in recent years, mango orchardsareaffected by numerous phytosanitary constraints like diseases and insect pests. Among the diseases, mango malformation is considered one of the most deadly for the mango tree. Since its discovery in 2009 in the south of Senegal, the disease has continued to spread in this area with incursions towards the northern part of the country. Few studies were dedicated to that pathogen in the Senegalese context. This study was carried out to help bring more light in the identity of the pathogen(s) causing this disease. Therefore 13 isolates of Fusarium isolates obtainedfrom mango malformation tissueswere characterized using morphological criteria and the molecular analysis. The 5.8S rDNA region of the internal transcribed spacer (ITS) was amplifiedusing ITS1 and ITS4 primer pairs. Sequence analysis and other analytical studiesshowed that the malformation of mango tree in southern Senegal is relatedto a diversity of Fusarium species. The morphological and molecular analysisallowed to identify several Fusarium strains with a very high degree of similarity (99.08 to 99.82%) with the species in the NCBI database ranged.

FIELD CASE INVESTIGATIONS OF MANGO MALFORMATION DISEASE IN FIVE DISTRICTS OF SOUTHERN PUNJAB AND ITS BIOLOGICAL MEDIATED MANAGEMENT UNDER CONTROLLED CONDITIONS

Mango is the king of fruits and keeps the status of national tree in some countries. Pakistani Mangoes are considered to the best in the world due to its shape, taste, flavor and deliciousness. Mango malformation is said to be the hundred century old disease consistently a source of losses for the mango industry. Extensive mango orchard’s survey showed a dynamic presence of the disease in the orchards. On the basis of visual systems the trees were evaluated and hence maximum disease severity (41.44) was recorded in District Layyah where the soils were observed more clayey as compared to the other districts of the South Punjab. Similarly, Multan ranked second in the infestation of Mango Malformation disease severity in the orchards while (30.11) was calculated in Lodhran followed by Muzaffar-Garh with (27.11) and Khanewal with (23.33). The fungus was identified as Fusarium mangiferae under the microscope and for the biological mediated management of the pathogen as hypothesized that if successful may be the best possible solution for the management of the disease in the orchards by utilizing the various Trichoderma spp. T. harzianum gave best control against F.mangiferae by depicting 71% inhibition against the pathogenic fungi. The use of Trichoderma spp against the pathogenic fungi will open new avenues in the biological control tactics of the plant diseases.

A Novel Disease of Big-Leaf Mahogany Caused by Two Fusarium Species in Mexico

Big-leaf mahogany (Swietenia macrophylla) is valued for its high-quality wood and use in urban landscapes in Mexico. During surveys of mango-producing areas in the central western region of Mexico, symptoms of malformation, the most important disease of mango in the area, were observed on big-leaf mahogany trees. The objectives of this research were to describe this new disease and determine its cause. Symptoms on big-leaf mahogany at four sites in Michoacán, Mexico resembled those of the vegetative phase of mango malformation, including compact, bunched growth of apical and lateral buds, with greatly shortened internodes and small leaves that curved back toward the supporting stem. Of 163 isolates that were recovered from symptomatic tissues, most were identified as Fusarium pseudocircinatum (n = 121) and F. mexicanum (n = 39) using molecular systematic data; two isolates represented unnamed phylospecies within the F. incarnatum-equiseti species complex (FIESC 20-d and FIESC 37-a) and another was in the F. solani species complex (FSSC 25-m). However, only F. mexicanum and F. pseudocircinatum induced malformation symptoms on 14-day-old seedlings of big-leaf mahogany. The results indicate that F. mexicanum and F. pseudocircinatum, previously reported in Mexico as causal agents of mango malformation disease, also affect big-leaf mahogany. This is the first report of this new disease and the first time that F. mexicanum was shown to affect a host other than mango.

Mango malformation: A fungal disease, physiological disorder or malady of stress

Mango (Mangifera indica L.) is one of the important commercial crops occupying a prominent place among various fruit crops. Mango malformation is a crucial malady in mango production leading to heavy economic loss. Malformation occurs in vegetative as well as floral tissue, later being virulent leading to loss of entire crop. Fusarium moniliforme is suggested as dominant causal agent of the disease although association of ‘stress ethylene’ with disease occurrence has also been studied. Fungal pathogens responsible for the malady are known to elevate the level of ‘stress ethylene’ in malformed plants. Various reports have been put forward to explain the etiology and control measures of the disease but nature and management of the disease is still a mystery. Hence, the present review aims at offering information regarding aspects of development and management of mango malformation.