Evaluating the Efficacy of Organic Approved Fungicides for the Control of Powdery Mildew in Squash

Powdery mildew grows well in environments with high humidity and moderate temperatures and can be problematic on crops in the Northeast. Cucurbit crops face powdery mildew and often downy mildew on a yearly basis and significant yields losses have been reported. The family of cucurbits is an important part of the diversified crop mix of a typical commercial vegetable farm in Vermont and throughout the Northeast. Growers have been using cultural practices, fungicides, and multiple plantings to mitigate crop loss from powdery mildew, however, the impact of the disease is seasonally dependent and still represents a consistent loss

Intracellular mycoparasites in action: interactions between powdery mildew fungi and Ampelomyces

Pycnidial fungi of the genus Ampelomyces are widespread intracellular mycoparasites of powdery mildew fungi worldwide. Their pycnidia are produced in hyphae, conidiophores and immature ascomata of their mycohosts. Thus, they suppress both the asexual and the sexual reproduction of the invaded powdery mildew mycelia, and then destroy them completely. Conidia of Ampelomyces are released from the intracellular pycnidia by the rupture of the pycnidial wall; conidia then germinate on the host plant surfaces, penetrate the intact hyphae of powdery mildew mycelia found in their vicinity and invade them internally growing from cell to cell through the septal pores of the mycohost. The early stage of mycoparasitism is apparently biotrophic, but the invaded cytoplasm then begins to die and a necrotrophic interaction results. Toxin production has not been detected in Ampelomyces, so it might act directly by invasion and destruction of the host cytoplasm. Experimental data showed that parasitized powdery mildew colonies can continue their growth, but their sporulation is stopped soon after Ampelomyces penetrated their mycelia. It is concluded that these mycoparasites represent a stress factor in the life cycle of their mycohosts but their role in the natural control of powdery mildew infections requires further investigations

Susceptibility to Apple Scab, Nectria Cancer and Powdery Mildew of Different Unsprayed Apple Varieties

Twentyfive apple varieties were evaluated for Apple scab (Venturia inaqualis), Nectria canker (Nectria galligena) and Powdery mildew (Podosphaera leucotricha) for 4 to 7 years. The trees were grown unsprayed. The weather conditions at the experimental orchard normally results in high infections of apple scab and low infections of powdery mildew. Infections of Apple scab is often seen also in scab resistant varieties. Williams Pride, Katinka and Katrina (scabresistant varieties) were the only varieties not showing scab in the experimental period. The two scabresistant varieties Angold and Produkta (varieties having a poor fruit quality) was unsusceptible to Nectria canker. The reference variety Elstar/Elshof was in all plantings among the most resistant varieties. Powdery mildew is not a problem at the experimental orchard. Most varieties had low susceptibility to Powdery mildew. Varieties with low susceptibility to diseases in general were Angold, Produkta, Rajka, Rubinola, Ahrista, Gerlinde, Gul Richard, Sukkertop, Katinka, Katrina, Marian and Primicia

Impact of foliar diseases in organically grown barley: Influence of fertilization, nutrient content in leaves, varietal disease resistance characteristics and yield potential

Significant increase in severity of powdery mildew,leaf rust and net blotch with increasing N-content in plant leaves 30 days after germination (all years where the relevant diseases were present at a substantial level). This may explain: · Most of the environmental main effects (field) on disease. · Effect of treatments, i.e., treament 4 resulted in reduced N/increased K content in leaves, which coincided with reduced levels of disease. We observed no clear effect of P, Ca, S, and Zn content in leaves on disease. Micronutrients as Cu, Mo and Mn showed significant effects on powdery mildew in one year but not the other; further interpretation may not be possible due to inter-correlation among the effect of micro-nutrients. The diseases had a significant yield reducing effect, in particular powdery mildew and net blotch, which occurred at highest severities. In addition, net blotch affected root development, resulting in significant shorter roots, whereas powdery mildew did not. The effect of disease on root length was of the same order of magnitude as the factor 'variety', but larger than effects of 'year'

Relationships between Oak powdery mildew incidence and severity and commensal fungi

Oak (Quercus robur) powdery mildew is a common and damaging fungal disease. In a local survey at Reading, UK, oak powdery mildew was common on trees of all height classes but was most common on trees of 3-9m. A variety of other fungal species were commonly found growing in association with oak powdery mildew colonies. The abundance of such fungi was estimated through stratified sample surveys for 2.5 years. The taxa most commonly associated with oak powdery mildew were Acremonium sp., Trichoderma sp., Ampelomyces/Phoma sp. and Leptosphaerulina australis. Nearly 90% of mildew colonies were associated with L. australis, which is not generally considered as a mycoparasite or antagonist, in contrast with the other three fungi. Abundance varied between June and October surveys. Acremonium sp. abundance was greater in summer samplings whereas L. australis and Trichoderma sp. abundances were greater in autumn samplings. Ampelomyces/Phoma sp. was never observed in the absence of powdery mildew. Relationships between the mildew-associated fungi and oak powdery mildew appeared curved and differed significantly between sampling years. L. australis was positively correlated with the other three associated fungi studied when powdery mildew was also present. The variety and high population densities of the mildew associated fungi suggest that they may be important in determining the final density of oak mildew and the damage caused by it

Resistance to the SDHI fungicides boscalid and fluopyram in Podosphaera xanthii from commercial cucurbit fields in Spain

Powdery mildew elicited by Podosphaera xanthii is a devastating disease of cucurbits worldwide and one of the most important diseases affecting these crops in Spain. Application of fungicides is the main control practice for managing P. xanthii; however, isolates resistant to multiple classes of site-specific fungicides have been recently reported in the Spanish cucurbit powdery mildew population. Succinate dehydrogenase inhibitors (SDHIs) constitute a relatively novel class of fungicides registered for powdery mildew control representing new alternatives for cucurbit growers. In the present study, 30 P. xanthii isolates were used to determine the effective concentration that reduces mycelial growth by 50% (EC50) to boscalid and fluopyram. The present study was also conducted to obtain discriminatory doses to monitor SDHI fungicide resistance in 180 P. xanthii isolates collected from several commercial cucurbit fields in Spain during 2017-2018. Three SDHI resistance patterns were observed in our population, which include patterns I (resistance to boscalid), II (resistance to fluopyram), and III (resistance to boscalid and fluopyram). The amino acid changes associated with these resistance patterns in the Sdh protein were also examined. Based on our results, SDHI fungicides are good alternatives for cucurbit powdery mildew control, although they should be applied with caution.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Incidence of Powdery Mildew on Cucurbit Plants and its Ecofriendly Management

Present paper deals with the study of powdery mildew incidence on different cucurbits hosts in different seasons and its biocontrol.  In Kharif season Sphaerotheca fuliginea was dominantly present on Cucurbita maxima, Lageneria siceraria and Cucurbita pepo, where as Erysiphe cichoracearum noted on Citrullus lanatus was not reported in 2005 and 2006.Cucurbita maxima, Lageneria siceraria, Luffa acutangula and Luffa cylindrica showed maximum occurrence of Sphaerotheca fuliginea in the rabbi season. Incidence of powdery mildew was mainly reported on the mature leaves followed by stem. Where as in some cases it was reported on tendril, flower and fruit. Dominant association of powdery mildew was mainly reported on basal leaf. However the incidence of powdery mildew was less on the younger leaves of cucurbits. Incidence of powdery mildew is more at post flowering and fruiting stage. However powdery mildew also reported at seedling stage of Cucurbita pepo and Cucurbita maxima. Neem leaf extract at15% concentration, Parthenium leaf at 10% concentrations. Ocimum leaf at 20% concentration, Citrus leaf at 20% concentration, Annona squamosa leaf at 10% concentration, Ipomea at 15% and Jowar leaf at 20% control the powdery mildew of cucurbits. Cow urine at 15% concentration proved to be effective to control powdery mildew on cucurbit. 20% to 25% of Butter milk spray successfully controlled the powdery mildew of cucurbit. Similarly 20% ash spray also found to be successful to control the growth of powdery mildew of cucurbits. Spray of Dashparni ark, a bi-product of plant and animal at 10% concentration inhibited the growth of Erysiphe cichoracearum and Sphaerotheca fuliginea.---1Department of Botany, ARTS and science college, Bhalod, tq. Yawal, Dist. Jalgaon (M.S.), India2Seed Pathology and Fungal Biotechnology Laboratory, Department of Botany, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad- 431004 (M.S.), India ---Please Cite This Article As: Vasant P. Pawar and Ashok M. Chavan. 2010. Incidence of Powdery Mildew on Cucurbit Plants and its Ecofriendly Management. J. Ecobiotechnol. 2(6):29-43.Â

Powdery Mildews on Vegetables

Powdery mildew is one of the most easily recognized fungal plant diseases. It is categorized by spots or patches of white-to-gray powder-like growth on foliage, stems, or fruit. Roughly 700 species exist that infect grasses, ornamentals, weeds, fruit trees, landscape trees, shrubs, and vegetables. The closely related species of fungi that cause powdery mildew are host-specific, meaning they cannot survive without the proper host. Powdery mildew fungi spread in conditions of low rainfall and hot temperatures, making Utah’s climate the perfect environment. This fact sheet provides information on powdery mildew and its management

The phytopathogen powdery mildew affects food-searching behavior and survival of Coccinella septempunctata

The diet of entomophagous coccinellids is mainly based on aphids and other food sources such as pollen, nectar, or fungal spores. Knowledge of their foraging behavior on plants infected by powdery mildew and their survival on fungal spores is currently limited. In this study, we investigated the olfactory response of Coccinella septempunctata to odor emission of barley plants infected by powdery mildew and their survival on fungal spores in the presence or absence of aphids. Odors released by powdery-mildew infected plants were more attractive for ladybirds compared to those of uninfected controls. After 3days, the survival rate of ladybirds feeding only on powdery-mildew spores was less than 50%, while for ladybirds feeding exclusively on Rhopalosiphum padi aphids, the survival rate was close to 90%. After 15days, the highest survival rate (almost 80%) was observed for ladybirds feeding on plants with both aphids and powdery mildew. Molecular analyses confirmed the presence of fungal spores in ladybird guts when feeding either on powdery mildew or on a mixed diet. Our results provide new insights into foraging behavior of entomophagous coccinellids revealing the potential of powdery mildew to be utilized as important non-essential food in a mixed diet, but also its lethal effect if consumed alone

Pewarisan Sifat Ketahanan Tanaman Melon (Cucumis Melo L.) terhadap Powdery Mildew (Podosphaera Xanthii (Castag.) Braun Et Shishkoff)

Powdery mildew is a fungal disease that causes subtantial losses in melon production around the world including Indonesia. Resistant melon cultivar to powdery mildew is important to increase melon production. Hence, the objectives of this study were to study melon resistance against powdery mildew and its inheritance. A F2 population was obtained from self pollination between F1 ♀ 371795 which derived from ♀ PI 371795 X ♂Action 434 and F1 ♀Action 434 which derived from ♀ Action 434 X ♂ PI 371795. In addition, a test cross population was produce by crossing between F1 with Action 434 as a recessive homozygote pa-rent. Furthermore, powdery mildew resistance in a F1, F2 and test cross populations were tested by inoculating powdery mildew which collected from Ngawi regency. The results were evaluated by Chi-square test (χ2). The results showed that a F1, F2 and test cross populations have different resistance levels to powdery mildew. The resistance to powdery mildew in a F2 ♀ PI 371795 population showed segregation and have 3:1 ratio of Mendel inheritance pattern. On the other hand, resistance to powdery mildew in a test cross with PI 371795 as a parent showed segregation with 1:1 ratio. While resistance in a F2 ♀ Action 434 and test cross populations with Action 434 as a parent did not express Mendel inheritance pattern. Based on the result it could be concluded thatn resistance to powdery mildew in PI 371795 as a female parent is controlled by a single dominant gene (pm-I), while resistance to powdery mildew in action 434 as a female parent is suppose to be controlled by several genes (oligogene). Melon (Cucumis melo L.) merupakan tanaman yang rentan terhadap hama dan penyakit. Powdery mildew (embun tepung) merupakan salah satu penyakit yang disebabkan oleh jamur tepung dan menyerang tanaman melon serta dapat menurunkan hasil produksi buah melon di seluruh dunia termasuk di Indonesia. Kultivar tanaman melon yang tahan terhadap powdery mildew diperlukan dalam meningkatkan hasil produksi buah melon. Penelitian ini bertujuan untuk mempelajari sifat ketahanan tanaman melon dan pola pewarisan sifat ketahanan tanaman melon terhadap powdery mildew. Dalam penelitian ini dilakukan persilangan tanaman melon F1 ♀ PI 371795 yang merupakan hasil persilangan antara ♀ PI 371795 dengan ♂ Action 434 dan F1 ♀ Action 434 yang merupakan hasil persilangan antara Action 434 dengan ♂ PI 371795 untuk mendapatkan tanaman melon F2. Selain itu juga dilakukan persilangan buatan antara tanaman F1 dengan Action 434 sebagai induk yang homozigot resesif. Kemudian dilakukan uji sifat ketahanan tanaman melon terhadap powdery mildew pada populasi F1, F2 dan test cross melalui inokulasi jamur tepung yang dikoleksi dari Kabupaten Ngawi. Hasil uji sifat ketahanan tanaman melon tersebut dievaluasi dengan menggunakan tes chi-square (χ2 ). Hasil penelitian menunjukkan bahwa tanaman melon pada populasi F1, F2 dan test cross memiliki tingkat ketahanan yang bervariasi terhadap powdery mildew. Sifat ketahanan tanaman melon pada populasi F2 ♀ PI 371795 mengalami segregasi dan mengikuti pola pewarisan Mendel dengan perbandingan 3:1. Demikian juga sifat ketahanan tanaman melon pada populasi test cross dengan induk PI 371795 mengikuti pola pewarisan Mendel dengan perbandingan 1:1. Sifat ketahanan tanaman melon pada populasi F2 ♀ Action 434 dan populasi test cross dengan induk Action 434 tidak mengikuti pola pewarisan Mendel. Berdasarkan hasil penelitian tersebut diketahui bahwa sifat ketahanan tanaman melon dengan induk betina PI 371795 dikendalikan oleh gen dominan tunggal (pm-I), sedangkan sifat ketahanan tanaman melon dengan induk betina Action 434 diduga dikendalikan oleh beberapa gen (oligogen)