Identification of new sources of resistance in Rajmash (Phaseolus vulgaris L.) against powdery mildew (Erysiphe polygoni) and stem rot (Sclerotinia sclerotiorum) diseases

One of the major constraints of black gram production is Powdery mildew (Erysiphe polygoni) disease. This study was an attempt of assess the efficacy of different chemicals against powdery mildew disease. The Experimental design was RCBD with three replication and Binamash-1 variety was planted under natural field conditions. Four chemicals viz. salicylic acid (1g/L), copper shulphate (0.5g/L), chitosan (0.1g/L) and thiovit (2g/L) was evaluated against powdery mildew disease. Those chemicals were applied 3 times with 7days interval after the disease initiation. Disease incidence and percent leaf area infection data was recorded three time after the application of treatments and other agronomic data was recorded after harvest. All the treatments were performed better than control in reducing the incidence of powdery mildew disease and percent leaf area infection. During the experimental period (Khrif -2, 2020), there was no incidence of other fungal foliar disease. Results represent that thiovit @ 2g/L performed best in controlling powdery mildew disease incidence (41%), percent leaf are infection (33%) and highest seed yield (520.57 kg/ha) among the treatments. We can conclude this study that, Thiovit (80% sulphur fungicide @ 2g/L) was best for controlling powdery mildew of black gram among the treatments and it (applied 3 times with 7days interval after the disease initiation) can be used for controlling this disease.

Mungbean is an important food crop, it is a source of carbohydrates, protein and B vitamine. Therefore the production must be increased. In increasing the production of mungbean, there are several constrains including disease infection. Leaf spot and powdery mildew are the main diseases on mungbean. Planting the resistant varieties to leaf spot / powdery mildew is an effective, easy, and inexpensive way. The aim of research is to get some resistant mungbean lines against leaf spot and powdery mildew disease. The research was conducted in the greenhouse of the Indonesian Legumes and Tuber Crops Research Institute, from May to September 2019. Evaluation of the resistance of mungbean lines to leaf spot and powdery mildew was carried out consecutively. The material tested was 20 mungbean breeding lines from the breeding section, with one resistant variety and one susceptible variety as a check. Inoculation was done by spraying the suspension of Cercospora cruenta spores of leaf spot, or Erysiphe polygoni spores of powdery mildew, with a density of 104 spores / ml in the afternoon. Observation of the intensity of leaf spot or powdery mildew disease is carried out three times, starting at one week after the first symptoms appeared. The results showed that out of 20 mungbean lines tested, there were no line that were resistant, 7 lines were moderately resistant and 13 lines were moderately susceptible to leaf spot disease. Out of 20 lines of mungbeans tested, 8 lines were resistant and 12 lines were moderately resistant to powdery mildew.

Field pea or “dry pea” (Pisum sativum L.) is an annual cool-season food legume which grows worldwide and is the major pulse crop in the highlands of Bale next to Faba bean. The experiment was conducted for two consecutive cropping seasons; 2011/12 and 2012/13 at Sinana agricultural research center (SARC) on-station research site. The objective was to find out the effect of Powdery mildew disease on field pea yield and yield components. Local field pea cultivar was used with a fungicide Benomyl at a rate of 2.5 kg/ha and four fungicide application schemes (spraying every 7 days, 14 days, 21 days and no fungicide spray) arranged in randomized complete block design (RCBD) with 3 replications. Logistic model (ln [y/ (1-y)]) was employed to analyze the Field experiment data using SAS procedure. The association between disease parameters and yield and yield components were assessed using regression and correlation techniques. ANOVA has shown significant difference (p ≤ 0.05) among treatments for disease severity. The highest diseases severity (41.98%) and Area Under Disease Progress Curve (AUDPC) (1458.33% days) and the lowest disease severity (13.89%) and AUDPC (471.15% days) were recorded from a plot with no fungicide treatment and plot sprayed every 7 days, respectively. Similarly, the highest disease progress rate (r) (0.044227 units-day-1) and the lowest r (-0.006122 units-day-1) were recorded from a plot with no fungicide treatment and plot sprayed every 7 days, respectively. Regarding the yield and yield related parameters; ANOVA has shown significant variations (P ≤ 0.05) between treatments for number of pods per plant, seeds per plant, TKW and grain yield. The highest number of pod per plant (21.75), seed per plant (89.5), TKW (189.81 g) and grain yield (2945.6 kg/ha) were recorded from plots sprayed every 7 days; while the lowest were from non-sprayed plots. On the other hand, the higher grain yield loss of 21.09% and the lowest loss (8.53%) were recorded from plots without fungicide spray and plot received spray at 7 days interval, respectively. The linear regression between powdery mildew severity index and grain yield revealed significant difference (P ≤ 0.0001) between treatments; and the estimated slope of the regression line obtained for Powdery mildew severity index was -34.16. Correlation analysis has shown that Powdery mildew disease severity have significantly strong negative correlation with grain yield (r= -0.76120, P ≤ 0.01). Similarly, grain yield has significant strong negative correlation (r= -0.76298, P ≤ 0.0001) with AUDPC.

India is the leading country in the world for cultivation, production and consumption of seed spices in general and cumin (Cuminum cyminum L.) in particular. The diseases such as blight, powdery mildew and wilt are the major constraints of low productivity of cumin. Among them, powdery mildew (Erysiphe polygoni L.) is very destructive disease of cumin and may cause loss in yield and quality deterioration, if proper and timely measures are not taken. At Seed Spices Research Station, Sardarkrushinagar Dantiwada Agricultural University, Jagudan (Gujarat), extensive research works for each of the chemicals have been carried out on powdery mildew management in cumin during last decade. The foliar application of metiram 55% + pyraclostrobin 5% WG @ 900 a.i.g ha (1500 g ha ) was found effective for the management of -1 -1 powdery mildew disease and increasing seed yield of cumin (2011). Two sprays of tebuconazole 25 WG @ 750 g ha proved its superiority against powdery mildew disease of cumin and it's also reported that -1 tebuconazole 25 WG is non-phytotoxic to cumin crop (2016). Two foliar sprays of difenoconazole @ 250 ml ha were found effective against powdery mildew of cumin (201 ). A combination of fungicides, -1 6 tebuconazole 50% + trifloxystrobin 25% WG @ 350 g ha proved its superiority against powdery mildew -1 disease of cumin with increase in the yield (2018). On the basis of the two years of investigation it has been concluded that captan 70% + hexaconazole 5%WP @ 750 g ha was found effective against powdery -1 mildew of cumin. Higher dose of captan 70% + hexaconazole 5% WP@ 3000 g ha did not produce any -1 phytotoxic symptoms on cumin crop at different crop stages during sprays as captan 70% + hexaconazole 5% WP is non-phytotoxic to cumin crop (2018). The hexaconazole 5 EC @ 1000 ml ha was found -1 effective against powdery mildew disease in cumin (2021). Foliar application of kresoxim methyl 50 SC @ 375 ml ha were found effective against and powdery mildew disease of cumin with higher seed yield -1 (2023).. KEYWORDS :Cumin, Erysiphe polygoni, fungicides powdery mildew

Investigation of the effects of Bacillus subtilis and Bacillus thuringiensis as Bio-agents against powdery mildew (Podosphaera xanthii) disease in zucchini (Cucurbita pepo L.)

The main purpose of this study is to determine the contents of 3 major phenolic compounds (gallic acid, catechin, and epicatechin) in 22 different grape cultivars/hybrids obtained from 2 different breeding programs. Additionally, changes in these phenolic components in the grape leaves of some resistant/tolerant species were determined in relation to powdery and downy mildew diseases in viticulture. The skin, pulp, and seeds of grape berries were analysed over two years, while changes in the phenolic contents of grape leaves were determined before and after these diseases for two years. The major phenolic contents of new hybrids/cultivars were compared with those of popular cultivars in different parts of the grapes, and significant differences in phenolic contents were found among hybrids/cultivars and different grape parts. Variations in the contents of phenolics in grape seeds, skins, and pulp were high, but seeds contained higher levels of these phenolics than pulp and skin. Analyses of the relationship between two viticultural diseases and phenolic changes in resistant/tolerant cultivars in relation with the susceptible “Italia” cultivar revealed that an increase in the content of the phenolic compounds was found after powdery mildew disease. Hybrids/cultivars with high phenolic contents are recommended to develop new superior cultivars, which are resistant to grape fungal diseases, in breeding programs.

Apple is an important fruit crop of temperate regions. The narrow genetic base of commercially cultivated apples has resulted in its vulnerability to a large number of fungal, bacterial, and viral pathogens. Apple breeders are always seeking new sources of resistance within the cross-compatible Malus species that can be deployed into elite genetic backgrounds. We have evaluated resistance to two major fungal diseases of apples: powdery mildew and frogeye leaf spot, using a germplasm collection of 174 Malus accessions to identify novel sources of genetic resistance. In 2020 and 2021, we evaluated these accessions for the incidence and severity of powdery mildew and frogeye leaf spot diseases at Cornell AgriTech, Geneva, New York, in a partially managed orchard. The severity and incidence of powdery mildew and frogeye leaf spot, as well as weather parameters were recorded in June, July, and August. Total incidence of powdery mildew and frogeye leaf spot infections increased from 33 to 38%, and 56 to 97% in 2020 and 2021, respectively. Our analysis showed that relative humidity and precipitation correlate with powdery mildew and frogeye leaf spot susceptibility. The predictor variables with highest impact to the variability of powdery mildew were accessions and relative humidity in May. A total of 65 Malus accessions were found to be resistant to powdery mildew, and only one accession showed moderate resistance to frogeye leaf spot. Several of these accessions belong to Malus hybrid species and domesticated apples and can therefore be potential sources of novel resistance alleles for apple breeding.

Kemal RA, Sandjaja EBL, Santosa AP, Ivan J. 2018. Short Communication: Identification of Mildew Locus O (MLO) genes in Durio zibethinus genome corresponding with the Powdery Mildew disease. Biodiversitas 19: 2204-2212. Mildew Locus O (MLO) is a protein consisting of seven transmembrane domains and appears in the various type of plants. MLO proteins are classified into seven clades. It is known that specific clades have different roles in a plant. MLOs from Clades IV and V have been linked to plant's susceptibility to Powdery Mildew (PM) disease. This study aimed to provide an overview of MLO genes present in durian (Durio zibethinus) genome. Bioinformatic analyses were conducted to analyze the phylogeny and structure of MLO genes and proteins in durian. The result showed that there were 20 putative DzMLO genes in durian, encoding 39 putative DzMLO proteins. Durian MLOs belong to Clade I-VI with one protein belongs to Clade IV and five proteins belong to Clade V. Those six MLO proteins shared a common motif in C-terminal and second intracellular domains. Putative alternative splicing and differential expressions were observed among Clade V DzMLO genes. These findings will facilitate the functional characterization of MLO genes and proteins in durian. Functional studies, especially on C-terminal and second intracellular domains, need to be conducted to elucidate the role of MLO in PM susceptibility in durian.

Powdery mildew caused by Erysiphe polygoni (DC)is one of the most economically important diseases in urdbean, and it occurs at later stages of crop growth, resulting in a yield loss of 20-50%. Powdery mildew control strategies include the use of chemicals and sources of host plant resistance. But due to the cost of chemicals, farmers rarely practice such control measures, and the usage of such fungicides will negatively affect the environment and especially human health. Therefore, the most effective way to control powdery mildew is the use of resistant varieties. Keeping this in view, disease screening studies were made to understand the identification of powdery mildew disease. Since powdery mildew may inflict heavy losses to the crop in the Telangana state, till now, none of the cultivars have been identified as resistant in Telangana against powdery mildew; therefore, this study was initiated to evaluate available urdbean germplasm for the identification of resistance sources to breed disease-resistant cultivars. In Rabi 2024-25, forty-nine genotypes were screened against powdery mildew diseases under field conditions along with susceptible and resistant checks. Out of 49 genotypes, none of the genotypes showed immune or resistant, five genotypes viz., MBG 1134, MBG 1169, MBG 1171, MBG 1123, and DBG 32-1 identified as moderately resistant, the remaining genotypes showed moderately susceptible (MBG-8, VBG 17-026) to highly susceptible (TU-512, PU-31, IPU 19-56, IPU 19-2).

Sclerotium rolfsii is a soil-borne pathogen causing stem and root rot disease with concomitant reduction in growth and yield of cowpea. Therefore, this study evaluated pathogenicity of S. rolfsii isolates and the management of root and stem rot disease using Trichoderma species. The isolates were obtained from cowpea rhizosphere and pathogenicity was determined using a susceptible cowpea genotype ITI0K–815-5 in an experiment arranged in a completely randomized design with four replications. In vitro and in vivo trials of Trichoderma spp. against a selected virulent isolate Sclerotium rolfsii (SR06) were conducted in the laboratory and screenhouse, respectively. All nine S. rolfsii isolates were pathogenic to the cowpea genotype, while isolate SR 06 was the most virulent with 85.56% infectivity rate. Treatments with T. virens and T. atroviride application reduced the disease incidences to 22.2% and 25.3%, respectively, compared to synthetic funguforce fungicide. Plants that were inoculated and treated with T. atroviride had significantly higher yield of 435 kg/ha than other treatments (p<0.037). Findings from this research encourages the incorporation of Trichoderma species in the integrated management of S. rolfsii pathogen and the incidence of stem and root rot disease in cowpea.

Botryosphaeria dothidea (B. dothidea) is a fungal pathogen commonly associated with stem canker, dieback, and rot disease in a variety of woody plants worldwide (Dong and Guo, 2020). In Korea, B. dothidea was reported to cause a disease problem to serval crops such as apple and blueberry (Kim, 1995; Choi, 2011). In early 2020, a typical symptom resembling the stem rot disease was spotted to occur at a plumcot cultivation area around Wanju (35.827870, 127.030380) province, Korea. At the early stage of infection, a small blister appeared on the plumcot branch and stem. However, as the blister extended, a light brown canker was observed appeared on the infected area and in some cases a sticky sap oozed from the branch bark crack. If not managed or treated properly, all leaves beyond the infection site will turn brown, wilt, and the whole plumcot tree eventually dies. A survey in the affected area showed that approximately 5% of the plumcot trees were infected which cause up to 10% reduction in total production. To identify the causal agent, symptomatic tissues were excised and surface sterilized with 70% ethanol for 30 sec followed by 1% NaClO for 30 sec before rinsing with sterile water, thrice. The samples were then dried with a piece of filter paper and later air-dried before being placed on a potato dextrose agar (PDA). The PDA plates were then incubated at 25°C for 5 days with 12 hours light/dark cycles period. Among several fungal isolates obtained, four were selected for further analyses. Morphological identification revealed that the fungal conidia were hyaline, ovoid, fusiform (type that rarely form a septum) and unicellular with an average size of 18 - 20 μm × 4.5 -5.5 μm (n = 50). These morphological characters have a strong resemblance to B. dothidea that described by Slipper et al., (2004). For molecular identification, Internal transcribed spacer (ITS), beta-tubulin (β-tubulin) and elongation factor 1 alpha (EF-1α) were amplified and sequenced using universal primer pairs ITS1/ITS4 (White et al., 1990), Bt2a/Bt2b (Glass and Donaldson, 1995) and EF1/EF2 (O'Donnell et al. 1998) respectively. Alignment analysis showed that ITS (LC602817), β-tubulin (LC602820) and EF-1α (LC602821) sequences were 99-100% identical to the orthologous genes identified in B. dothidea infecting soybean in China [MW130133 (identity 537/536 bp), MW147482 (identity 394/394 bp) and MW147481 (identify 250/250 bp) respectively] (Chen et al. 2021). However, phylogenetic analysis of concatenated ITS, β-tubulin and EF-1α genes sequence established the identity of these isolate as B. dothidea. Due to the 100% identical at the molecular level, isolate NIHHS 20-262 was selected as a representative for further analysis. For the pathogenicity test, fungal mycelium (via PDA plug) was used as a source of inoculum for both intact and detached plumcot stems trials. For the intact trial, mycelium was inoculated on the wounded spots of ten plumcot stems that grew at the NIHHS trial farm. Ten days post-inoculation (dpi), disease symptoms i.e. stem colour turn from greenish to dark brown was observed at the inoculated sites. For the detached trial, mycelium was inoculated on the wounded spots of ten detached plumcot stems. The inoculated stems were kept in a closed container to maintain 90% humidity before incubated at 25ºC in the dark. Interestingly, on the detached stems, disease symptoms (greenish colour turn to dark brown) were observed to appear seven days early compare to intact stems. A sterile PDA plug replacing fungal mycelium served as a negative control and the result shows no symptoms were observed on either intact or detached control stems. For consistency purposes, pathogenicity tests on intact stems were performed on three different plumcot trees, whereas three biological replicates for detached stems. Isolation and re-identification of two colonies from the infected sites (intact and detached stems) were attempted and the results obtained were identical to the original isolate, thus fulfilling Koch's postulates. Local farmers described this disease as a "certain death disease" in plumcot. Therefore, accurate identification of B. dothidea as the causal agent is critical for effective disease management to minimise qualitative and quantitative losses in the plumcot industry. Although has been reported to cause dieback disease in blueberry in Korea (Choi, 2011), to our knowledge, this is the first study to report B. dothidea causing stem rot diseases on the plumcot trees in Korea.

Sclerotinia stem rot (SR) disease emerged as a potential threat in most mustard‐growing regions globally. Sclerotinia sclerotiorum, a necrotrophic pathogen, causes considerable damage to the crop under congenial environments. The sclerotia even under adverse conditions can survive up to 5 years in the soil. The use of resistant sources is the only mean to combat the pathogen. The development of an effective inoculation technique can facilitate the identification of new sources of resistance rapidly. Investigations on resistant sources using Potato Dextrose Agar (PDA) medium for artificial stem inoculation are ongoing under the All India Coordinated Research Project (AICRP) on rapeseed‐mustard for many years but no resistant sources could been identified. In the present study, two non‐injury stem inoculation techniques using sorghum grains and PDA medium as a basal medium were tested on 11 brassica entries for up to three consecutive years. Results revealed that sorghum grain‐based inoculum was found efficient for disease development and lesion formation in brassica entries compared with PDA‐based inoculum. Among the entries, a maximum disease incidence of 42.3% was recorded in entry DRMR 5206 followed by DRMRSJ‐20, DRMRSJ‐22 and DRMR 2017‐8 with 42.1%, 41.8% and 41.3% SR incidence, respectively. In PDA disc inoculation maximum SR incidence of 30.8% was observed in DRMRSJ‐26 followed by DRMR 5206, DRMRSJ‐25 and DRMRSJ‐2017‐18 with 27.5%–24.9%, respectively. Lesion length was more in entries inoculated with fungal mycelium multiplied on sorghum grains compared with the PDA disc inoculation method. The statistical analysis and results of p‐value (<.00001) showed a significant difference between tested methodologies. Thus, the sorghum grain‐based inoculation technique is an appropriate, economic and effective non‐injury inoculation technique for artificial screening against S. sclerotiorum in the mustard crop. This technique can be used to screen a large number of brassica entries more efficiently with less labour and time.

Powdery mildew disease is the most important disease of mustard (Brassica Juncea) which is highly sensitive to weather condition particularly temperature and humidity. To ascertain the relationship between weather variables and powdery mildew disease of mustard crop at Sardarkrushinagar, weekly powdery mildew data of 12 years (2010-11 to 2021-22) was collected from Centre for Oilseed Research, S.D. Agricultural University, Sardarkrushinagar. The data were pooled over the year and correlated with corresponding weather parameters recorded in Agromet Observatory, S.D. Agricultural University, Sardarkrushinagar. The forewarning regression equation was developed with the help of weather variables to predict the disease incidence. The results revealed that the maximum and minimum temperature ranged 26.2 to 38.1oC and 8.7 to 18.5oC respectively found congenial for disease incidence. The weather variables like maximum temperature (Tmax) and minimum temperature (Tmin) correlated significantly positive with powdery mildew disease. While morning relative humidity (RH I) and evening relative humidity (RH II) correlated significantly negative with disease severity. The impact of rainfall (RF), sunshine hour (SSH) and wind speed (WS) found positive but non-significant on powdery mildew disease. The weather variables those have significant relationship with powdery mildew disease, were used to develop multiple regression model. The regression equation Y = 62.837 + 8.072*Tmax – 3.919*RH1 developed with maximum temperature and morning relative humidity caused up to 96 % variability in the powdery mildew disease. Hence the combined effect of Tmax and RH1 was more pronounced and most influencing weather parameters on powdery mildew disease. Therefore, model could be used for predicting the powdery mildew disease well in advance.

Sunflower (Helianthus annuus L.), an important edible oil seed crop, is prone to severe attack by necrosis, Alternaria leaf spot and powdery mildew diseases which lead to poor seed germination and loss of seedling vigour and yield. The present study was conducted for 3 consecutive years with the aim to manage these foliar diseases under field conditions through seed priming (bio or chemo) followed by fungicide/insecticide spray. The result revealed that among the treatments tested, seed priming with carbendazim @ 2 g + thiamethoxam @ 4 g kg−1 seeds followed by foliar spray of propiconazole @ 0.1% + thiamethoxam @ 0.04% twice (30 and 45 days after sowing) gave effective control of necrosis (2.27%), leaf spot (19.6 PDI) and powdery mildew (17.94 PDI) diseases with seed yield increase (1443 kg ha−1) over control. This was followed by Trichoderma viride priming which recorded 7.1% necrosis, 38 PDI of leaf spot and 36.31 PDI of powdery mildew. Seed bio-or chemo-priming promoted higher and uniform seed germination under field conditions. Seed priming with carbendazim @ 2 g kg−1 + thiamethoxam @ 4 g kg−1 along with two foliar sprays of propiconazole @ 0.1% + thiamethoxam @ 0.04% (30 and 45 DAS) were effective.

Rubber (Hevea brasiliensis) latex production is crucial to the local economy, yet Xishuangbanna's climate is considered sub-optimal for rubber cultivation. The prevalence of the powdery mildew disease (Oidium heveae) in this region has decreased the annual latex yield by 20%. Rubber latex yield is influenced by several factors, including temperature, disease, other biotic conditions, and plantation management. However, the interrelationships and potential influencing networks between rubber latex yield and these factors are rarely quantitatively assessed, and understanding their impacts on latex yield could inform better management practices. To address this gap, we investigated the effects of temperature, phenology, and powdery mildew disease on rubber latex yield in March using observational data on daily rubber latex yield combined with detailed phenology, powdery mildew, and temperature data from 2004 to 2010 in a state farm in the Xishuangbanna, Yunnan, China. We found that the critical influencing periods of daily temperature difference (or diurnal temperature difference) on the rubber latex yield were during Nov 27-Jan 19 and Jan 21-Mar 17. Partial least square regression analysis and variance partitioning analysis were conducted on the 35 phenological variables, eight powdery mildew-related variables, and two climatic variables. The most influential factors were identified as the factors of the daily temperature differences during Jan-Mar, the duration of leaf flushing phenology, and mean and maximum percentage of leaves infected by powdery mildew. Subsequent canonical correlation analysis and linear regression found that temperature difference directly affected the rubber latex yield and indirectly affected the yield through phenology and powdery mildew disease. Raised daily temperature differences from Jan to Mar had the greatest impact, leading to a higher rubber latex yield. Our comprehensive quantitative assessment revealed the relative importance of antecedent daily temperature differences, phenology, and powdery mildew disease as well as their complex interconnections in influencing rubber latex yield. Our findings are essential tofuture studies on both powdery mildew disease and rubber latex yield, and alsodevelop rubber latex models.