Chemical control of stem-end rot on mango fruits in the San Francisco river Valley.

The objective of this study was to assess the efficacy of some fungicides in reducing the incidence of stem-end rot when applied after flowering onset

Pathogenicity and fungicide sensitivity of the causal agent of postharvest stem end rot disease of mango in Ghana

ABSTRACTStudies were carried out on the stem end rot disease of mango in Ghana. The incidence and severity of the disease were evaluated on mango fruits collected from major mango growing areas of Ghana. The causal agent was isolated on media and identified. The pathogenicity of the fungus and its cross-infection potential were determined on mango, avocado, papaya and banana fruits. The sensitivity of the pathogen to fungicides was determined by assessing radial mycelial growth on potato dextrose agar (PDA) amended with nine different fungicides (Bendazim, Funguran, Ivory, Topsin, Asuoku master, Kocide, Mirage, Sulphur 80 and Copper oxychloride). Stem end rot disease was prevalent in the major mango growing areas of Ghana. Two pathogens, Lasiodiplodia theobromae and Colletotrichum gloeosporioides were isolated from the disease lesions. However, only the former was able to cause stem end rot disease symptoms on the artificially inoculated fruits, confirming it as the causal agent of the disease. It was also found to be highly susceptible to Bendazim, Ivory, Topsin, Asuoku master and Mirage, whilst it was resistant to Funguran, Kocide, Sulphur 80 and Copper oxychloride.Original sciencitic paper. Received 30 Apr 15; revised 17 Oct 14

Characterization And Pathogenicity Of Fungi Associated With Stem-End Rot Of Mango Fruit

Mango (Mangifera indica L.) is one of the popular fruit crops in Malaysia and stem-end rot is a serious post-harvest disease of mango fruits. The present study was conducted to determine the stem-end rot fungal pathogens. Mango fruits were collected from orchard, night market and supermarket at northern states of Peninsular Malaysia. Fungal isolates were isolated from lesion of stem-end rot from cultivars Chok Anan, Falan, Golek, Black Gold, Harumanis, Waterlily, Raja and Apple Mango. The fungal isolates were identified using morphological and molecular characteristics

Distribution and Characterization of Diseases of Dragon Fruit (Hylocereus Spp.) in Peninsular Malaysia

Field surveys were conducted from December 2007 to August 2008 at 43 dragon fruit-orchards in Peninsular Malaysia with 50 posts of sampled plants per location. The results revealed that among recorded diseases, anthracnose, brown spot and necrotic spot were encountered in almost all sampled states with the range of frequency around 50 to 100%; whereas fruit brown rot was only found in Negeri Sembilan with frequency of 33.33%. Meanwhile, other diseases such as fruit fungal soft rot, stem end rot and bacterial soft rot occurred in 2, 5 and 6 surveyed states, respectively. Statistical analysis showed that the occurrence of anthracnose and necrotic spot diseases were maximum in Malacca with incidence and severity level around 58.00%; 21.20% and 72.00%; 30.00%, respectively. Meanwhile, the maximum occurrences of bacterial soft rot, brown spot and stem end rot were documented in Johore, Negeri Sembilan and Kelantan with incidence and severity levels of about 17.33%; 4.53%, 94.00%; 25.87%, and 14.00%; 4.20%, respectively. These diseases have strong relationships of incidence and severity with the range of R2 value around 0.8995 to 0.9978. Pearson correlation analysis resulted in the incidence of anthracnose which was significantly correlated with necrotic spot (r value of 0.852 at 0.05 level); whereas bacterial soft rot and brown spot were significantly interrelated with each other at the 0.01 level with r value of 0.515. Similarly, the Pearson coefficient correlation also revealed that bacterial soft rot was negatively correlated with temperature (r value of -0.478 at 0.01 level). The positive correlations were shown by bacterial soft rot and brown spot against altitude with r value of 0.508 and 0.523, respectively at 0.01 level. These diseases were categorized according to the characteristics of symptoms found on diseased plants and group of pathogenic agents. Although a number of bacteria and fungi species could be isolated and identified correspondingly based on their responses to biochemical sources within BiOLOG® Microplate as well as their cultural and morphological characteristics, the pathogenicity test showed that only some (e.g. Enterobacter cloacae, Bipolaris sp., Botryosphaeria sp., Colletotrichum gloeosporioides, and Monilinia sp.) positively resulted in similar symptoms with diseased plants in the field. In the mean time, the presence of viral infection was successfully detected on young stems with necrotic small mottle or spot symptoms

Potato Wilt and Stem-end Rot Caused by Fusarium eumartii

The present study was undertaken to obtain more information regarding the pathogenicity of Fusarium eumartii and to compare its action with F. oxysporum, in order to distinguish between and to determine the relative importance of the diseases produced by these two organisms. An effort was also made to explain the many negative results of isolation studies reported by various investigators, as well as the inconsistent results often reported in studies of the transmission of wilt by infected tubers. Investigations dealing with the effect of certain environmental conditions on the occurrence of the disease were also undertaken. All of the experiments recorded in this publication were conducted with the Bliss Triumph variety. It is hoped that the results presented here will materially assist in clearing up some of the long disputed points concerning the wilt of potatoes, and open up a new line of investigation in the study of the action of these wilt-producing organisms and their control

Quantification of postharvest diseases of guava accessions cultivated in organic system

Among the postharvest diseases that occur in guava, anthracnose, black spot and stem-end rot are the most common. The incidence and diversity of these diseases depend on the host genotype. This study aimed to identify and quantify the postharvest diseases of guava accessions cultivated in organic system. For the characterization of diseases, 30 fruits from 48 accessions were evaluated in a completely randomized design. Anthracnose and black spot were the most frequent postharvest diseases in guava. The Vermelha Redonda (Shimoda), L5P21, L3P12, EEF-3, IAC-4 -Unesp and Monte Alto -Comum 1 accessions stood out with the lowest incidence of anthracnose and black spot, while L4P13, L1P2 and Creme Arredondada (Unesp) showed the highest incidence of anthracnose, black spot and stem-end rot. The Fusicoccum sp., Phomopsis sp., Phoma sp., Dothiorella sp. and Lasiodiplodia sp. pathogens were identified as the main responsible for causing stem-end rot symptoms

Controlling plant and fruit diseases in strawberry fields

Grey mould and stem-end rot affect the strawberry industry in Australia. Losses of 10% of the crop are equivalent to a loss of $46 million across the different growing areas. The effect of different fungicides on the control of grey mould and stem-end rot affecting ‘Festival’ strawberry plants was studied in south-east Queensland over three years. This work followed recent changes to the use pattern for the multi-site fungicides thiram and captan, which can now be used more regularly than previously in Australia. There was a restriction on the use of captan with no more than five sprays allowed in a season. Thiram could be used only up to the first flowering. A program based on captan and thiram along with several single-site fungicides during wet weather controlled grey mould and stem-end rot. These treatments in turn provided high marketable yields. Applications of a plant-defence promoter, plant extracts, organic acids, fatty acids, a salt, four bacteria, and a fungus were not as successful as the standard program, even when the soft fungicides were applied alternately with thiram and captan. The plant-defence promoter acibenzolar-S-methyl, organic acids, B. subtilus (strain QST 713), B. amyloliquefaciens and potassium bicarbonate gave intermediate control. In contrast, B. subtilus (strain MBI 600), Streptomyces lydicus, Trichoderma harzianum, potassium salts of fatty acids, and two plant extracts were ineffective. A strategy based on thiram and captan applied alternately, with the addition of single-site fungicides during wet weather provided the best control of disease, with 3 to 4% losses. Control plots had losses of 25 to 38%. The soft chemicals were less effective than the programs based on captan, thiram and single-site fungicides. The use of the thiram and captan in rotation with other fungicides from different chemical groups in wet weather will reduce the risk of fungicide resistance and extend the useful life of registered products. This strategy has not been available to growers previously

The application of low pressure storage to maintain the quality of zucchinis

Zucchini (Cucurbita pepo var. cylindrica) were stored at low pressure (4 kPa) at 10°C at 100% relative humidity for 11 days. Fruit quality was examined upon removal and after being transferred to normal atmosphere (101 kPa) at 20°C for three days. Zucchinis stored at low pressure exhibited a 50% reduction in stem-end browning compared with fruit stored at atmospheric pressure (101 kPa) at 10°C. The benefit of low pressure treatment was maintained after the additional three days storage at normal atmospheric pressure at 20°C. Indeed, low pressure treated fruit transferred to regular atmosphere 20°C for three days possessed a significantly lower incidence of postharvest rot compared to fruit stored at regular atmospheric pressure at 10°C. Zucchinis stored at low pressure showed higher levels of acceptability (28% and 36%, respectively) compared to fruit stored at regular atmospheres at 10°C for both assessment times.<br/