Abstract:
Anthracnose, caused by Colletotrichum gloeosporioides, is a foliage, pre and post harvest disease of guava. Artificially inoculated leaves by C. gloeosporioides were performed to understand the infection processes of anthracnose at various intervals after inoculation compared with naturally infected were performed. The first evidence of penetration into the leaf was observed 48 h after inoculation, fungal hyphae colonized epiderms tissues through cuticle layer and spread inter and intracellular with evidence of cell cell plasmolysis, disorganization and dark brown discoloration of some parenchymatous cells (P). In advanced stages, seventy two hours after artificial inoculation (hai) the pathogen spread to adjoining invaded tissues causing complete breakdown of the inoculated tissues and hyphae (h) extensively ramified in the invaded intercellular spaces, endodermal cells and xylem units also, mycelia were also present in and within the xylem (Xy) elements. Transfer sections of After 96 h, all the invaded cells became necrotized and vascular bundle was completely plugged with gum like substances. No differences were found between naturally infected and artificially inoculated (in vitro) leaves , the pathogen invasion and symptom development process is similar for both conditions. C. gloeosporioides is able to invade different tissues causing changes in cells structure and caused plasmolysis and discoloration of parenchymatous cells as well as necrosis in different leaf tissue. These necrotized tissues increase with the time of inocubation.

Key wards: Anatomical changes, guava anthracnose disease, Colletotrichum gloeosporioides

Abstract:
This study was performed during 2011-2012 in four different locations in Egypt toinvestigate the fungal species associated with graft union cause grafting failure process.Phomopsis viticola was the most frequent pathogen isolated from graft failure seedlings ingraft union in all localities followed by Botryodiplodia theobromae. Whereas, the otherisolated fungi (Phoma sp., Fusarium solani and Alternaria solani) were negligible.Different approaches for disease management including chemical and biological methodswere carried out. Among different fungicides, Topsin M 70% (WP) and Kemazed 50%(WP) gave the best results for controlling fungal pathogens cause graft failure, followed byBillis 38% (WG), Saprol 19% (DC), Syllit 40% (SC) and Conazol 10% (EC). As alternativecontrol means, Bio-Zied (Trichoderma album), Rhizo-in (Bacillus subtilis) and Bio-Arc(Bacillus megaterium) reduced the percentage of disease incidence by 40.06 %, 26.92 %and 25.18 %, respectively. Based on the results obtained by this study, phytopathogenicfungi can be considered one of the most important factors influencing graft union successof grapevine in Egypt.

Key words: Verticillium dahliae; Mangifera indica; wilt; salt; Egypt

Abstract:
Seven fungal genera were isolated from diseased mango seedlings originated from seed grown in different nurseries located in three Egyptian governorates during seasons of 2010 and 2011. The fungus Botryodiplodia theobromae Pat. was the most frequently isolated fungi followed by Rhizoctonia solani Kühn. and Fusarium solani (Mart) Sacc. while Pestalotiopsis sp. was the lowest frequent one. The most pathogenic fungus was B. theobromae compared to Pestalatiopsis sp., which caused the lowest percentage of root rot infection. Anantomical changes studies of transverse and longitudinal root sections, using light microscope after 30 days from artificial infection, revealed that the cortex layer was completely colonized by B. theobromae, F. solani compared with R. solani, which attack and colonized firstly the lateral and hairy roots. This colonization was associated with disorganized epidermal and cortical cells in addition to a dark brown color consisting of crushed and necrotic cells and tissues. Such disorders were not observed in un-inoculated mango seedling. Forty five days after artificial inoculation with B. theobromae or F. solani the fungal hyphae were clearly noticed in both xylem vessels and xylem parenchyma causing necrosis and deposition of dark material like gum as well as abundant production of tylosis. There were correlation between histological changes and disease development, at the time of inoculation, the foliar appeared vigorously green colored and erect. The inoculated seedling after 30 day was paler, less vigorous, and less rigid than those of non-inoculated ones. In the end of experimental after 45 days, seedlings became yellow, wilting and finally the seedlings were dead and turned brown.

Key wards: Anatomical changes, Soil borne fungi, mango, root-rot diseases, Botryodiplodia theobromae, Rhizoctonia solani, Fusarium solani.

Abstract:
Cephaleuros virescens is a plant parasitic green alga, causing several diseases on guava such as leaf spot, fruit spot and branches canker as well as defoliation and twigs die-back in tropical and subtropical countries. During the growing season of 2012 – 2013, examination of guava (Psidium guajava L.) trees growing in orchards and nurseries at Qalubyia and Giza Governorates revealed that several trees were observed with symptoms and signs of fruit and leaf spots as well as branch canker diseases (Fig.) . Symptoms on leaves and fruits often observed as roughly circular spots with irregular borders in reddish brown to reddish purple or rust brown with reddish margin, crowded or scattered, especially in the early stages. Spots on guava leaves were observed as intercellular, full-thickness necrosis, destroying both upper and lower epidermal cell layers and all intervening, tissue discoloration beneath the bark. The presence of an orange velvet-like growth ( sporangiophores and sporangia ) of the pathogen was also observed . Zoospores were released when sporangia placed in water drops . The causal pathogen was isolated from guava infected tissues, purified and identified as Cephaleuros virescens