Percent Disease Incidence Research Articles

The incidence of pokkah boeng in indigenous and exotic sugarcane (Saccharum officinarum) clones

Pokkah boeng (Fusarium moniliforme J L Sheldon) is a minor fungal disease in sugarcane (Saccharum officinarum L.), characterized by malformed leaves. The disease incidence was surveyed at two locations in Haryana (Karnal and Kaithal) from 2010 to 2013. Chlorotic phase infection was prevalent in the study area. The percent disease incidence ranged from 6.90 to 25.30%, the highest incidence was recorded during 2013. A total of 138 subtropical sugarcane varieties, 40 pre-release clones and 182 exotic clones were screened against the disease under natural epiphytotic condition at Karnal. Most of the clones (80.83%) were resistant (120 clones out of 360) or moderately resistant (171 clones out of 360) to pokkah boeng. Subtropical varieties such as BO 137, Co 0238, CoH 110, CoJ 83, CoJ 85, CoS 8432, CoS 8436, CoS 88230, CoS 03251, CoS 03252, CoSe 95436, CoSe 01434 and UP 0097 were moderately susceptible hence strong seed health programme is suggested to contain the disease. Fourteen clones, viz. Co 425, Co 12027, Co 10036, Co 0331, M 165/38, H 45-2120, B 46-199, Q 64, PR 1058, CP 81-1384, F 65-554, POJ 6688, EPC 37-069 and H 44-3098 were susceptible to pokkah boeng hence this information may be taken into account while deciding the merit of the clones for hybridization. Autumn planted canes manifested less disease incidence than spring planted canes. Canes around field border and broad leaved clones showed higher disease incidence. However, the incidence did not vary between plant crop and ratoon crops. There were no association between pokkah boeng incidence and top borer attack but their combined damage would be detrimental to the crop. About 92.67% of pokkah boeng infected plants recovered growth, without fungicide spray, as the age of the crop advances and with change in weather.

Molecular and Cultural Characterization of Alternaria brassicae Infecting Cauliflower in Uttar Pradesh, India

The Alternaria blight or leaf blight (Alternaria brassicae) causes severe damage to cauliflower at curd formation and seed setting stage. Roving survey revealed that the disease incidence on cauliflower in different farmer’s fields ranged from 10 to 40 % with an average incidence of 20 % in Uttar Pradesh. Twenty-three (23) isolates of A. brassicae were collected from different cultivars in Uttar Pradesh and characterized for cultural, morphological, pathogenic and molecular variations. Based on the pathogenicity, isolates of A. brassicae were rated as virulent or less virulent based on the percentage disease incidence on cv. Hajipur local. Most of the isolates showed smooth mycelial growth with circular, irregular margin and without concentric zonation. The colony colour is white, dark brown to light brown and pinkish in white. Significant morphological variations in conidial length, conidial width, and number of horizontal septa were observed in all the isolates. The maximum length of conidia ranged from 150 to 122 μm with 8 to 9 transverse and 2 vertical septation. Further the genetic diversity of isolates based on RAPD-PCR using sixteen random primers were produced on clarity, repeatability and the number of polymorphic bands in all the isolates. Cluster analysis of DNA fragments was performed using NTSYSpc V2.2 based on UPGMA method and Jacard coefficient. Based on the analysis the isolates represented four major groups with 75 % similarity.

Influence of Growth Regulators Combined with Chemicals to Improve Postharvest Fruit Quality in Banana cv. Nendran (Musa AAB)

A study was undertaken at TNAU, Coimbatore to envisage the effect of different chemicals and growth regulators in combination with Thiabendazole (Fungicide) on post-harvest quality and shelf life of banana cv. Nendran (French Plantain Musa AAB). Various concentration of, GA3, BA, CaCl2 and Hot water treatment either alone or in combination with Thiabendazole was applied to fruits after harvest to study their impact on post-harvest quality and shelf life. Exogenous application of chemicals, growth regulators in combination with Thiabendazole significantly decreased post-harvest disease incidence leading to increase in post- harvest fruit quality and shelf life. Among the treatments, post-harvest dipping of fruits in 150 ppm GA3 + 200 ppm Thiabendazole significantly increased firmness (3.70 kg/cm2) titrable acidity (0.09%) and storage life of fruits (18.00 days). While the parameters like PLW (13.53%), TSS (25.45oB), total sugars (18.88%), reducing sugars (17.11%) and percent disease incidence (5.55) was observed minimum in the same treatment after 12th day of storage.

English

The excessive application of pesticides for agricultural production has raised quite some concern about environmental safety and sustainability. To reduce environmental impact of pesticide overuse, there is an increasing interest in using different elicitors including Jasmonic acid (JA) to induce resistance against pathogen and insect in crop. Chilli ( Capsicum annuum L.), which is an important vegetable cum spice crop around the world. The aims of this study were to compare the effectiveness of Jasmonic acid on growth, Phyto-physiological responses, yield and viruses control in chilli plant. It was evaluated the effectiveness of single spray of JA (JA1), double spray of JA (JA2), conventional pesticide (Malathion 50%) and without any of those or control. The experimental results showed that pesticide-treated plants perform much better at early growth stages and become less competitive to JA2 treatment at maturity. Double spray of jasmonic acid showed less stress symptoms in different antioxidant enzymes activities (GPX, APX and CAT), reduce percentage of disease incidence and severity as well as improve growth and yielding characters of chilli plant. Therefore application of Jasmonic acid in chilli could be a possible alternative of pesticide application and its two times exogenous spray (0.5mM) is most effective.

Assessment of Disease Intensity and Evaluation of Enset Clones against Bacterial Wilt (<I>Xanthomonas campestris pv. Musacearum</I>) in Tikur Inchini and Jibat Districts of West Shewa, Ethiopia

Enset ( Ensete ventricosum Welw. Cheesman) is an important staple food crops in Ethiopia, which is widely cultivated in Southern and South western parts of the country. However, its production has been threatened by one of the devastating bacterial disease caused by Xanthomonas campestris pv. musacearum (Xcm) in enset cultivated areas of the country. The management of Enset Bacterial Wilt (EBW) is important to maximize the crop's yield. Therefore, the present investigation is to determine the disease intensity (prevalence and incidence) of EBW in enset growing areas of Tikur Inchini and Jibat districts of West Shewa, Ethiopia and to evaluate the field grown enset clones for resistance/tolerance to EBW using pot culture condition. Field survey of EBW disease was carried out in the main growing season during September-November, 2012. The disease assessment was made in the enset cultivated fields of selected localities in both districts. The EBW infection was recorded in different levels in both districts. A total of 75 enset cultivated fields were assessed from Tikur Inchini district, of which, 67 fields were affected with different levels of EBW disease prevalence (89.3%). The highest incidence (27%) of EBW was recorded in Waldo Hindhe locality and the lowest incidence was recorded in Homi Hane locality (14 %). From Jibat district, a total of 75 enset cultivated fields were assessed, of which, 65 fields were affected with different levels of disease prevalence (86.7%). The incidence of EBW was recorded highest in Munyo Abayi locality (25%) and the lowest incidence was recorded in Munyo Witate locality (14%). This data indicated that the disease was widely distributed with a very destructive incidence in survey areas of Tikur Inchini and Jibat districts. To evaluate the field grown enset clones for resistance/tolerance to Xcm, twenty number of enset clones collected from both the districts were assessed, using artificial inoculation under pot culture condition. The relative susceptibility of the cultivars to EBW was evaluated three months after inoculation based on wilt incidence. All Xcm inoculated enset clones expanded disease symptoms to different intensity levels after 15 to 30 days inoculation. The varieties of the disease frequency were variable ranging from 19.3 to 100%. Out of the 20 enset clones, only 6 enset clones confirmed a mean infection incidence less than 50 percent. The present investigation displays that the enset genetic copies fluctuate enset bacterial wilt by their reaction. After 30 days of introduction of inoculation, the enset clones 'Warke Bidu', 'Awenyi', and 'Kekar' showed 100 % disease symptoms. The disease symptom was detected from 'Meziya', 'Hiniba', 'Bedadet' and Warke Dima between 21 and 30 days successive inoculation. The remaining enset clones were relatively resistant/tolerant after inoculation of Xcm. Among all, 'Meziya' was found to have the lowest percentage of disease incidence (19.31%) followed by 'Hiniba' (30.18%) and 'Bedadet' (34.26%). Based on the results, none of the enset clones had resistance to Xcm. The results indicated that the enset clones, 'Meziya', 'Hiniba', 'Bedadet' and 'Warke Dima' have exhibited better resistant/tolerant clones to the bacterial wilt, under artificial inoculation conditions and these enset clones should be considered as most tolerant/resistant clones to the pathogen which could be used as a bacterial wilt management component. The results of the study indicated that the use of resistant/tolerant enset clones is one of the best approaches in the management of EBW, cheaper to the farmers and safer to environments. Hence, a resistant and tolerant outcome of the enset clones confirmed by the wilt pathogen should be further assessed in contrast to a great number of Xanthomonas campestris pv. musacearum , isolates in field conditions.

Evaluation of cotton leaf curl virus resistance in BC1, BC2, and BC3 progenies from an interspecific cross between Gossypium arboreum and Gossypium hirsutum.

Cotton leaf curl virus disease (CLCuD) is an important constraint to cotton production. The resistance of G. arboreum to this devastating disease is well documented. In the present investigation, we explored the possibility of transferring genes for resistance to CLCuD from G. arboreum (2n = 26) cv 15-Mollisoni into G. hirsutum (2n = 52) cv CRSM-38 through conventional breeding. We investigated the cytology of the BC1 to BC3 progenies of direct and reciprocal crosses of G. arboreum and G. hirsutum and evaluated their resistance to CLCuD. The F1 progenies were completely resistant to this disease, while a decrease in resistance was observed in all backcross generations. As backcrossing progressed, the disease incidence increased in BC1 (1.7–2.0%), BC2 (1.8–4.0%), and BC3 (4.2–7.0%). However, the disease incidence was much lower than that of the check variety CIM-496, with a CLCuD incidence of 96%. Additionally, the disease incidence percentage was lower in the direct cross 2(G. arboreum)×G. hirsutum than in that of G. hirsutum×G. arboreum. Phenotypic resemblance of BC1 ∼BC3 progenies to G. arboreum confirmed the success of cross between the two species. Cytological studies of CLCuD-resistant plants revealed that the frequency of univalents and multivalents was high in BC1, with sterile or partially fertile plants, but low in BC2 (in both combinations), with shy bearing plants. In BC3, most of the plants exhibited normal bearing ability due to the high frequency of chromosome associations (bivalents). The assessment of CLCuD through grafting showed that the BC1 to BC3 progenies were highly resistant to this disease. Thus, this study successfully demonstrates the possibility of introgressing CLCuD resistance genes from G. arboreum to G. hirsutum.

Lipoxygenase-related defense response induced by Trichoderma viride against Aspergillus niger Van Tieghem, inciting collar rot in groundnut (Arachis hypogaea L.)

Groundnut varieties grown in non-infested soil (T1), pathogen (Aspergillus niger)-infested soil (T2), and seed treatment with Trichoderma viride JAU60 followed by challenge with fungal pathogen (T3), showed significant differences in percent disease incidence of collar rot in pot culture. Percent disease incidence was higher in GG-13, GG-20 (susceptible) followed by GAUG-10 (moderate), and minimum in J-11, GG-2 (tolerant varieties) in A. niger-infested pot culture at 15 days after sowing (DAS). Seed treatment (T3) of T. viride reduced approximately 51% to 58% disease incidence in different groundnut varieties. The lipid peroxidation product – malondialdehyde (MDA) – content was found to be higher in susceptible varieties grown in pathogen-infested soil (T2) and it was significantly reduced to 56% under T. viride treatment (T3) at 12 DAS. However, tolerant varieties reduced the MDA content by 60% in T3 as compared with the T2 at an earlier stage (9 DAS). The lipoxygenase (LOX) activity rose approximately 3.5-fold in tolerant varieties upon infection (T2) and groundnut seed treated with T. viride (T3) at 12 DAS. Trichoderma treatment (T3) maintained a high level of LOX compared with T2, particularly in tolerant varieties. The pathogen infection ability was positively correlated with LOX activity in tolerant and moderately tolerant varieties of T2 seedlings. MDA content was positively correlated with disease incidence in susceptible varieties followed by induction of LOX activity under T. viride JAU60 treatment (T3). T. viride JAU60 signifies induction of a LOX-related defense response to combat the collar rot disease incidence in groundnut seedlings.

English

Leaf blight caused by Rhizoctonia solani is one of the most serious diseases that cause damage to turmeric crop. Fifty percent disease incidence was observed in turmeric growing areas of Andhiyur (Erode district) and Mettur (Salem district) of Tamil Nadu, India. The antifungal efficacy of botanicals, bioagents and fungicides were tested against R. solani in vitro. It was observed that seed extract and oil cake of Madhuca longifolia suppressed the mycelia growth (34.81; 49.63%), sclerotial formation (100%) and production of biomass (2.18; 2.41 mg) of R. solani followed by leaf extracts of Azadirachta indica and Littorina littorea. Among the bioagents native isolate of BSoya1 of Bacillus spp., Cg1 of Chaetomium spp., Pf1 of Pseudomonas spp. and Tv1 of Trichoderma spp. shown more than 50% antagonistic effect on mycelia growth and 100% on sclerotial formation. The complete fungal growth inhibition was observed in Nativo and Bavistin fungicides amended medium. Then, the basal soil application of mahua cake and T. viride in the ratio of 1:2 (1 g of mahua cake mixed with 2 g T. viride per kg of pot soil) followed by foliar spray of Nativo @ 0.5% significantly mitigated the leaf blight (8.6%) over the inoculated control (50.51%) in pot culture experiments. Key words: Turmeric, efficacy, fungicides, bioagents, botanicals, Rhizoctonia solani.

Penggunaan Cendawan Mikoriza Arbuskula (Cma) Untuk Mengendalikan Fusarium Oxysporum F.sp. Cubense Dan Nematoda Radopholus Similis Pada Tanaman Pisang Barangan (Musa Paradisiaca L.) Di Rumah Kaca

The use of mycorrhizal arbuscula fungi (MAF) to control the Fusarium oxysporum f.sp.cubense and Radopholus similis on Barangan banana (Musa paradisiaca L.) in glasshouse.The research was to knew the effectivity of MAF in controling Fusarium wilt and R. similison Barangan Banana. The research was carried out in glasshouse of Agriculture Faculty,University of Sumatera Utara, Medan since May until December 2012. The method of thisresearch was Randomized Complete Design Non Factorial with nine treatment, namelycontrol, inoculation of MAF, inoculation of R. similis, inoculation F. oxysporum f.sp cubense,inoculation of mycorrhizal, R. similis & Foc, inoculation of Foc one week later MAF and R.similis, inoculation of R. similis one week later CMA dan Foc inoculation of MAF one weeklater Foc one week later R. similis; inoculation of MAF one week later R. similis one weeklater Foc and with three replication. The parameters are incubation period (days), diseaseincidence (%), and disease severity (%). The results showed that fastest incubation period inthe treatment M0R0F1 are 11 days and the lowest in the treatment M1R3F2, M1R2F3 are 20days. The highest percentage of disease incidence in the treatment M0R0F1 are 88.89% andthe lowest in the treatment M1R2F3 are 22.22%. The highest disease severity in the treatmentM0R0F1 are 35.56% and the lowest in the treatment M1R2F3 are 8.89%.Keywords: Mycorrhizal Arbuscula Fungi, Fusarium oxysporum f.sp cubense,Radopholus similis, banana

PENGARUH MUSIM TERHADAP PERKEMBANGAN Atelocauda digitata, PENYEBAB PENYAKIT KARAT PADA Acacia auricaliformis DI YOGYAKARTA

ABSTRACTSeasonal effect on the growth of Atelocauda digitata, the cause of rust disease on Acacia auriculiformis in Yogyakarta. The research was aimed to determine the growth of Atelocauda digitata which attacks Acacia auriculiformis in Gunung Kidul, Yogyakarta and determine the process of A. digitata infection on A. auriculiformis. Quantification of the presence of pathogen and the damage as part of tree health monitoring was represented by the percentage of disease incidence and severity, that was used as a benchmark of A. digitata dynamics. Pathogenic organisms were confirmed by pathogenicity test. The process of infection was studied microscopically and macroscopically. Percentage of disease incidence and severity of all three observation plots during the rainy and the dry season were dynamic, with the highest damage discovered in Plot 5. A. digitata infecting A. auriculiformis produces three types of spores, namely teliospores, uredospores and aeciospores. The hyphae infected the leaf tissue two days after inoculation through stomata. Intracellular hyphae were found five days after inoculation.

Effect of certain traditional cultural practices for the management of blast disease of rice in Manipur agro-climatic conditions

Field experiments were conducted during kharif 2010 and 2011 seasons to ascertain the effect of various traditional cultural practices for the management of blast disease of rice (variety RCM10). Cultural practices viz. sowing method, sowing dates and weeding frequencies were considered. Among the treatments, timely transplanting reduces the disease parameters such as disease incidence, disease severity, AUDPC and rate of infection as compared to broadcasting method. However, no significant effect of seed sowing method was observed. Clean cultivation with three or more weeding showed relatively less disease parameters. Index Terms: Blast, rice, broadcasting, transplantation, sowing date, weeding, traditional. I. Introduction Rice is the most important staple food of Manipur. In north-east India, cultivated mostly under rain fed conditions during kharif season as both dry land and wetland crop. Blast disease of rice caused by Pyricularia grisea (Cook) Sacc. is one of the most widely distributed foliar disease of rice cultivated under upland and wetland systems as in other parts of the globe where rice is grown (Singh, 2005) (5). It occurs every year under the agro-climatic conditions (temperature, relative humidity, rainfall) of Manipur in mild or severe form. As the use of costly chemical fungicides for the control of blast disease has many harmful effects to the environment. Cultural practices practiced by the traditional rice farmers provide a scope for the economically and eco-friendly management of the disease without affecting the environment. As such these practices reduce the use of synthetic chemicals for the control of the disease to some extent although it is a labour intensive. Therefore an attempt has been made to ascertain the effect of the cultural practices for the management of blast disease of rice under the prevailing climatic conditions of Manipur with an objective of encouraging traditional rice farmers for improvement of eco-friendly practices and refraining them from the use of chemicals. The objective of the present study is to enhance knowledge to the poor and marginal farmers in understanding various eco-friendly management practices which are simple and affordable. II. Materials And Methods Field trials were carried out during kharif seasons (2010 and 2011) in a sick farmer's field which shows the occurrence of blast disease of rice during the last three years of cropping seasons. The experiment was laid out in a randomized block design in 3 × 3 m 2 plots with three replications for each treatment. A higher dose of nitrogenous fertilizer @ 100kg/ha as against the recommended dose (60 kg/ha) was applied to make the crop more prone to disease. Traditional cultural practices such as sowing method (broadcasting and transplanting), sowing dates (15 th June, 30 th June and 15 th July) and weeding (one time weeding, two times weeding and three times weeding) were considered to see their effects on the epidemiology of blast disease of rice. Seed broadcasting and nursery planting (25 days old seedlings were transplanted in the field @ 2-3 plants per hill at a spacing of 20 cm row to row and 15 cm plant to plant) for transplanting treatment were done on the same day. For sowing dates, the seed nurseries were raised keeping 15 days of interval and transplanted to the field keeping the same interval. Hand weeding was done after 20 days of transplantation and subsequent weeding was done at 15 days interval. The disease parameters like percent disease incidence (D.I. %) and percent disease severity (D.S. %) were observed at fortnightly intervals starting from the occurrence of the disease till the flowering stage of the plant. Data on D.I.(%), D.S.(%), the area under disease progress curve (AUDPC) and apparent rate of disease infection (r) were using simple random sampling and calculated as follows.

Role of associative bacterial interaction in the induction of tuber rot incidence in cassava (Manihot esculenta Crantz)

Cassava (Manihot esculenta Crantz), one of the leading staples in the world, has considerable scope for integration into emerging markets through efficient and environmentally sound production of a diversified range of high quality, competitive products for food, feed and industry. One of the major reasons attributed to the low productivity of cassava in India is the incidence of tuber rot in cassava incited by Phytophthora palmivora. Usually, an array of microorganisms is involved in rotting of cassava tubers in the field and in postharvest conditions. Unfortunately, the disease management practices focus mainly on fungal pathogens. In this article, we tried to investigate the role of associative bacterial pathogens in induction of tuber rot of cassava, the potential of the bacteria with P. palmivora in causing disease incidence, spread and rotting. The bacteria and P. palmivora were originally isolated from tuber rot infected cassava from the field having a disease incidence percentage of above 40%, checked for pathogenicity and were proven for Koch postulate. The detached tubers of disease resistant (cv. Sree Pathmanabha) and susceptible cultivars (cv. M4) of cassava were used for the study. The effect of bacterial association was studied in Cassava agar plate assay, in detached tubers and in in planta experiments in in vitro glass house conditions. The bacterial isolates were identified as Gram-negative coco bacilli of class Pseudomonas, Erwinia amylovora and Achromobacter denitrificans.

EFFICACY OF SOME ORGANIC COMPOUNDS AGAINST ROOT ROT WILT DISEASES OF OLIVE TRANSPLANTS AND THEIR GROWTH RESPONSE IN NEW VALLEY GOVERNORATE, EGYPT

Root rot and wilt disease complex were detected during disease survey carried out through two successive seasons (2011 & 2012) in several olive transplants nurseries and new orchards at ElKharga, Baris, Balat, El-Dakhla and El-Farafrah districts of New Valley governorate. Percentage of disease incidence and severity on olive transplants in surveyed districts varied. The highest means either in disease incidence or severity (60.8 and 48.7%, respectively) were recorded at El-Dakhla district followed by ElKharga (52.1 and 43.6%). Fusarium oxysporum was the most frequently isolated fungus at the five locations tested, followed by F. solani and Rhizoctonia solani, while Macrophomina phaseolina was the least one. Efficiency of seven organic compounds and one fungicide, as soil drench treatment, varied in reducing disease incidence and severity under greenhouse conditions. All organic compounds tested reduced the diseases severity than the control. Humic acid, Inicium, Fulvital and Bio-Health compounds gave the highest protection compared to untreated transplants (control). Humic acid, however, was significantly superior than the other, whil EMI was the least. All treatments significantly increased plant height, number of leaf plant -1, leaf area and fresh & dry weights

Using Commercial Compost as Control Measures against Cucumber Root-Rot Disease

Five commercial composts were evaluated to suppress the root-rot pathogens (Fusarium solani (Mart.) App. and Wr, Pythium ultimum Trow, Rhizoctonia solani Kuhn, and Sclerotium rolfsii Sacc.) of cucumber plants under in vitro and greenhouse conditions. In vitro tests showed that all tested unautoclaved and unfiltrated composts water extracts (CWEs) had inhibitor effect against pathogenic fungi, compared to autoclaved and filtrated ones. Also, the inhibitor effects of 40 bacteria and 15 fungi isolated from composts were tested against the mycelial growth of cucumber root-rot pathogens. Twenty two bacteria and twelve fungal isolates had antagonistic effect against root-rot pathogens. The antagonistic fungal isolates were identified as 6 isolates belong to the genus Aspergillus spp., 5 isolates belong to the genus Penicillium spp. and one isolate belong to the genus Chaetomium spp. Under greenhouse conditions, the obtained results in pot experiment using artificial infested soil with cucumber root-rot pathogens showed that the compost amended soil reduced the percentage of disease incidence, pathogenic fungi population, and improved the cucumber vegetative parameters as shoot length, root length, fresh weight, and dry weight. These results suggested that composts are consequently considered as control measure against cucumber root-rot pathogens.

Control of green mould of citrus by using Trichoderma harzianum, humic acid or garlic

Penicillium digitatum, an aggressive fungus causes post-harvest decay of mandarin sweet orange and Washington navel. In vitro Trichoderma harzianum or humic acid (HA) or powdered cloves of garlic caused inhibition of fungal growth of isolates P1 and P2. Under storage conditions, the fruit citrus is protected by using T. harzianum with standard volume 2.0 ml (9.6 × 106 conidia/ml) and application 24 h before inoculation reduces disease incidence and disease severity after seven days from inoculation with P. digitatum spore suspension (1.0 × 106 spores/ml) compared to control. Spraying the fruit citrus by standard volume of 2.0 ml of either HA or powder cloves of garlic 1% on each fruit 24 h before inoculation reduces disease incidence and disease severity after seven days from inoculation with P. digitatum (1.0 × 106 spores/ml) compared to control. The lowest percentage of disease incidence and disease severity were associated with powder of cloves garlic and followed by HA and T. harzianum during two growing seasons compared with the untreated and control.

Tolerance to Fusarium wilt and anthracnose diseases and changes of antioxidative activity in mycorrhizal cyclamen

Mycorrhizal associations imply a remarkable reprogramming of functions in both plant and fungal symbionts. This consequent alteration on plant physiology has a clear impact on the plant responses to biotic stress management. As a consequence, a pot experiment was conducted to study the interactions between the arbuscular mycorrhizal fungus (AMF) Glomus fasciculatum and the two pathogens Fusarium oxysporum and Colletotrichum gloeosporioides and subsequent effect on growth, disease tolerance and the changes in antioxidative ability in cyclamen plants under growth chamber condition were investigated. At plant maturity, inoculation with F. oxysporum and C. gloeosporioides, responsible for Fusarium wilt and anthracnose of cyclamen respectively, significantly reduced shoot and root dry weights, increased both the disease incidence percentage and showed lower antioxidative activity viz. superoxide dismutase (SOD), ascorbate peroxidase (APX), ascorbic acid (AA) and polyphenol contents in plants. In contrast, the growth response and biomass production of cyclamen plants inoculated with AMF was significantly higher than the nonmycorrhizal control plants, both in the presence and absence of the pathogens. Mycorrhization enhanced plants to reduce the Fusarium wilt and anthracnose incidence compared to nonmycorrhizal controls. In every case, without and with pathogen association, plants inoculated with AMF increased the antioxidant (SOD, APX, AA and polyphenol) production compared to control plants. The results demonstrate that AMF have the ability to induce resistance against Fusarium wilt and anthracnose in cyclamen by increasing the antioxidative activity in plants, which promoted plant growth, biomass production and drastically reduced the disease incidence in cyclamen.

Plant extracts for controlling the post-harvest anthracnose of banana fruit

In banana, fruit rot is incited by Colletotrichum musae which has been the most serious post-harvest disease of immature and mature fruit. The usual control by fungicides prohibited in many countries reduces their commercial value. Therefore, two experiments were conducted to evaluate the antimicrobial activity of alternative products to the synthetic fungicides. First, berries naturally infected by anthracnose were immersed into Azadirachta indica and citric extracts at 2 and 4% (v/v) for 3 minutes and stored for 11 days under environmental conditions. Next, other berries were immersed into essential oil emulsions of Allium sativum, Copaifera langsdorfii, Cinnamomum zeylanicum and Eugenia caryophyllata at 5% for 3 minutes but stored for 11 days. Berries immersed into distilled water were used as control-treatments. The percentage of disease incidence observed in the control-treatment was similar to the ones observed in the extract of A. indica at 2%. The control-treatment showed disease severity of 75.13% and the percentage of disease control was 20.85%. Fruit immersed into distilled water presented less effectiveness than the ones immersed into citric extracts, which promoted the highest effectiveness. Citric extract at 4% was the most efficient treatment because the disease incidence was 19.44%, the disease severity was 9.34% and the disease control was 90.16%. Less severity and, consequently, more disease control were achieved by immersing the berries into the emulsion of essential oil of A. sativum, followed by treatments with C. langsdorfii, E. caryophyllata and C. zeylanicum.

Influence of plant spacing, seed rhizome size and cultivars on the incidence of rhizome rot and wilt disease complex of ginger

Rhizome rot and wilt disease complex is the important production constraints of ginger cultivation in hill agro-ecological region of West Bengal. In the present study, attempt have been made to manage the problem by adjusting plant spacing, seed rhizome size and as well as by selection of suitable cultivars available in the region. Plant spacing of 25 × 30 cm was found to be optimum for better crop return and lower disease incidence. Considering both lower percentage disease incidence and higher yield, seed rhizome size of 50 to 75 g was found to be optimum for ginger planting. Mother rhizome extraction/removal that is, the common practice followed by ginger growers in the region had an additive effect on incidence of rhizome rot and wilt disease complex of ginger. None of the locally available germplasm tested was found to be tolerant against rhizome rot and wilt disease complex of ginger, however, cultivar “Majauley” may be considered as moderately susceptible and “Bhaisey” and “Gorubathaney” are considered as highly susceptible germplasm.

SURVEY AND CONTROL TRIALS OF ROOT ROT / WILT OF DATE PALM OFFSHOOTS IN NEW VALLEY GOVERNORATE

Root rot/wilt of date palm offshoots was surveyed during seasons of 2011 and 2012 starting from March to October in nurseries and orchards in different major areas of the New Valley Governorate (at El-Kharga, Paris, El-Dakhla, El-Farafrah and Eastern Owinat). The average percentage of disease incidence ranged between 48.0 and 68.6% and the severity of the disease ranged between 37.7 and 53.7%. Eleven fugal species were isolated from rotted roots of diseased offshoots. Frequency of the isolated fungi varied according to the locality, where Fusarium oxysporum was the most frequent fungus in all localities followed by F. solani, F. moniliforme, F. semitectium, and F. equiseti. Pathogenicity tests showed that Fusarium oxysporum, F. solani, F. moniliforme, F. equiseti and F. semitectium were pathogenic to date palm offshoots, but they differed in their pathogenic potentials. Fusarium oxysporum, F. solani and F. moniliforme caused the highest disease incidence and severity. Efficiency of five different fungicides (Kemazed, Maxim XL, Moncut, Rizolex T and Topsin M70) varied in reducing the disease., Kemazed, Maxim XL Rizolex-T and Topsin M70 at conc. 100-200 ug/me and Moncut at 200 ug/me completely inhibited growth of the tested fungi in vitro . Under field conditions, Topsin M70, Maxim XL, Rizolex-T and Kemazed, were the most effective fungicides in controlling root rot d wilt of date palm offshoot

Role of antibiosis on suppression of bacterial common blight disease in French bean by Paenibacillus polymyxa strain HKA-15

Paenibacillus polymyxa strain HKA-15, a soybean bacterial endophyte showed strong antagonism against bacterial common blight pathogen Xanthomonas campestris pv. phaseoli strains M-5 and CP-1-1. In agar diffusion assay, the antibacterial metabolite from P. polymyxa HKA-15 showed a clear zone of inhibition against M-5 and CP-1-1. Under phytotron conditions, the biocontrol activity of P. polymyxa HKA-15 against bacterial common blight pathogen X. campestris pv. phaseoli M-5 was assessed. At four days after inoculation of M-5, lowest mean disease rate (MDR) (1.13) and percent disease incidence (PDI) (28.25) were recorded in streptomycin sulphate at 100 ppm as positive chemical treatment. The application of crude metabolite from P. polymyxa HKA-15 at 100 ppm was on par with positive chemical control in suppression of bacterial common blight disease in French bean plants. Key words: Antibacterial activity, biocontrol, French bean, Paenibacillus polymyxa , Xanthomonas campestris pv. phaseoli .