scholarly journals Field and Growth Chamber Evaluation of Powdery Mildew Disease on Deciduous Azaleas

HortScience ◽  
2010 ◽  
Vol 45 (5) ◽  
pp. 784-789 ◽  
Author(s):  
Michael C. Long ◽  
Stephen L. Krebs ◽  
Stan C. Hokanson
Keyword(s):  
Powdery Mildew ◽  
Field Trial ◽  
Leaf Surface ◽  
Low Cost ◽  
Field Performance ◽  
Resistance Breeding ◽  
Field Resistance ◽  
Growth Chamber ◽  
Leaf Surfaces ◽  
Highly Correlated

Forty-one deciduous azalea (Rhododendron subgen. Pentanthera G. Don) cultivars were assessed for powdery mildew (PM) resistance in a two-location, 3-year field trial. Disease severity (percent leaf area affected) on abaxial leaf surfaces was used to rate the level of field resistance. This measure was proportional to (r = 0.83) but higher than estimates from corresponding adaxial surfaces. Eleven of these cultivars (27%) appeared to be highly resistant under field conditions, i.e., evidence of PM on the leaves was zero or near zero. Twenty-three of the cultivars evaluated in the field experiment were also evaluated in a growth chamber experiment. In contrast to the field study, PM was more severe on the adaxial leaf surface in the growth chamber but still highly correlated with the abaxial response (r = 0.93). Based on adaxial disease scores, no cultivars in the growth chamber experiments were completely resistant. Growth chamber disease ratings based on either leaf surface were predictive of field performance (r2 = 0.62), suggesting use of the chambers could serve as a low-cost, off-season, early selection component of a deciduous azalea PM resistance breeding program.

scholarly journals First Report of Powdery Mildew on Euryops pectinatus in Italy

Plant Disease ◽  
2002 ◽  
Vol 86 (8) ◽  
pp. 920-920
Author(s):  
A. Garibaldi ◽  
A. Minuto ◽  
D. Bertetti ◽  
M. L. Gullino
Keyword(s):  
Powdery Mildew ◽  
Leaf Surface ◽  
Northern Italy ◽  
Growth Chamber ◽  
Growth Reduction ◽  
First Report ◽  
Similar Disease ◽  
Commercial Farms ◽  
White Mycelium ◽  
Sphaerotheca Fusca

Euryops pectinatus is grown in Italy for landscape use in parks and gardens. In 2001, severe outbreaks of a previously unknown powdery mildew were observed in commercial farms located in Albenga (northern Italy). All green parts (leaves, stems, and petioles) became covered with a white mycelium. Infections were particularly severe on the upper leaf surface. With progress of the disease, infected leaves turned yellow and died. The presence of powdery mildew infections on leaves and stems only rarely was linked to growth reduction. Conidia were hyaline, cylindric to slightly doliform, did not show fibrosin bodies, borne in chains, and measured 24 to 41 × 12 to 20 μm. Cleistothecia were not observed. The pathogen was identified as Oidium sp. subgen. Fibroidium (1). Pathogenicity was confirmed by gently pressing diseased leaves on leaves of healthy E. pectinatus plants. Inoculated plants were maintained in a growth chamber at 20 to 24°C. After 12 to 14 days, powdery mildew symptoms developed. A similar disease of E. pectinatus was observed in 1999 in California and identified as being caused by Podosphaera (Sphaerotheca) fusca (2). It is possible that the powdery mildew observed in Italy belongs to the same species, also considering that recently the two genera, Podosphaera and Sphaerotheca, have been unified in the genus Podosphaera (1). References: (1) U. Braun and S. Takamatsu. Schlechtendalia 4:1, 2000. (2) G. S. Saenz et al. Plant Dis. 84:1048, 2000.

scholarly journals Assessment of Resistance to Witches'-Broom Disease in Clonal and Segregating Populations of Theobroma cacao

Plant Disease ◽  
2004 ◽  
Vol 88 (8) ◽  
pp. 797-803 ◽  
Author(s):  
S. Surujdeo-Maharaj ◽  
P. Umaharan ◽  
D. R. Butler
Keyword(s):  
Incubation Period ◽  
Theobroma Cacao ◽  
Resistance Breeding ◽  
Field Resistance ◽  
Individual Plant ◽  
Germplasm Collections ◽  
Optimum Sample Size ◽  
Accuracy And Precision ◽  
Broom Disease ◽  
Highly Correlated

Fourteen clonal genotypes of cacao (Theobroma cacao) and their open-pollinated progenies were tested for their resistance to witches'-broom disease (Crinipellis perniciosa) using an agar-droplet inoculation method in separate, replicated greenhouse experiments. Nine measures of resistance were evaluated for precision, ability to discriminate between levels for resistance, and their correlation to field resistance. Correlations among the various measures of resistance were also ascertained. Data were re-examined to determine the accuracy and precision associated with individual plant measurement as well as the optimum sample size to assess segregating populations for resistance. The agar-droplet method was able to effectively discriminate various levels of resistance. Incubation period provided a precise, sensitive, valid, and heritable measure of resistance to C. perniciosa. Furthermore, incubation period was highly correlated with broom size and moderately correlated with broom frequency, two epidemiologically important components of resistance. The study also shows that 25 to 30 open-pollinated progeny are sufficient to provide a good estimate of a parent's resistance. The implications of the findings for identifying resistance among cacao germplasm collections as well as within segregating populations for resistance breeding are discussed.

scholarly journals Effect of powdery mildew (Erysiphe graminis f.sp. tritici) on spring wheat in Finland

1973 ◽  
Vol 45 (5) ◽  
pp. 461-467
Author(s):  
Oiva Nissinen
Keyword(s):  
Powdery Mildew ◽  
Spring Wheat ◽  
Relative Yield ◽  
Resistance Breeding ◽  
Field Resistance ◽  
Erysiphe Graminis ◽  
Grain Weight ◽  
Grain Yields ◽  
1000 Grain Weight

In 1970–72 the effect of powdery mildew on Finnish spring wheats with different field resistance was studied. For the mildew control 1 kg/ha Karathane WD (22.5 % Dinocap) was used. These investigations showed that mildew control increased grain yields in susceptible varieties by 2.4 to 6.6 %. The 1000-grain weight increased by 2.2 to 5.3 %, respectively. On the more field resistant spring wheats mildew control had no particular effect. Mildew control evened out the relative yield differences between the varieties. The paper includes notes on the occurrence of mildew in Finland while the need for resistance breeding is also discussed.

scholarly journals Spectroscopic Estimation of N Concentration in Wheat Organs for Assessing N Remobilization Under Different Irrigation Regimes

2021 ◽  
Vol 12 ◽  
Author(s):  
Wei Li ◽  
Xiaonan Zhou ◽  
Kang Yu ◽  
Zhen Zhang ◽  
Yang Liu ◽  
...  
Keyword(s):  
Low Cost ◽  
Resistance Breeding ◽  
Hyperspectral Data ◽  
Least Squares Regression ◽  
Irrigation Regimes ◽  
N Concentration ◽  
Organ Specific ◽  
Powder Samples ◽  
N Remobilization ◽  
Highly Correlated

Nitrogen (N) remobilization is a critical process that provides substantial N to winter wheat grains for improving yield productivity. Here, the remobilization of N from anthesis to maturity in two wheat cultivars under three irrigation regimes was measured and its relationship to organ N concentration was examined. Based on spectral data of organ powder samples, partial least squares regression (PLSR) models were calibrated to estimate N concentration (Nmass) and validated against laboratory-based measurements. Although spectral reflectance could accurately estimate Nmass, the PLSR-based Nmass-spectra predictive model was found to be organ-specific, organs at the top canopy (chaff and top three leaves) received the best predictions (R2 > 0.88). In addition, N remobilization efficiency (NRE) in the top two leaves and top third internode was highly correlated with its corresponding N concentration change (ΔNmass) with an R2 of 0.90. ΔNmass of the top first internode (TIN1) explained 78% variation of the whole-plant NRE. This study provides a proof of concept for estimating N concentration and assessing N remobilization using hyperspectral data of individual organs, which offers a non-chemical and low-cost approach to screen germplasms for an optimal NRE in drought-resistance breeding.

Incidence of powdery mildew on cucurbit plants in Katsina, Nigeria

2019 ◽  
pp. 05-09
Keyword(s):  
Powdery Mildew ◽  
Low Cost ◽  
Frequency Of Occurrence ◽  
Sphaerotheca Fuliginea ◽  
Causal Organism ◽  
Powdery Mildews ◽  
Powdery Mildew Disease ◽  
Important Disease

The presence study deals with powdery mildews in various cucurbits in Katsina city (Barhim Estate, Kofar Durbi, Kofar Sauri, Kofar Marusa and Low Cost), Nigeria. The finding shows that the areas infested with powdery mildew is one of the important disease of cucurbits. The Sphaerotheca fuliginea was identified to be the causal organism present on all observed cucurbits in the study. Highest frequency of disease was found in Kofar Sauri(79%) fallowed by Kofar Marusa (68%), Kofar Durbi (66%), Barhim Estate (65%) and the lowest frequency of occurrence of disease was found in Low Cost (55%).The intensity of the disease was moderate to severe in general but it was high in many fields, the area-wise variation was also noticed. On vegetables, the highest frequency of occurrence of powdery mildew disease was observed on L. cylindrica (76.4%) followed by C. moschata (60%), C. sativus (59.3%), C. vulgaris (53.9%) and lowest was found on C. melo (44.4%). The highest intensity of disease was found on C. moschata, followed by L. cylindrica, C. sativus, C. vulgaris and C. melo.

RESISTANCE TO MILDEW OF SELECTION FAMILY OF RED CURRANT THE BELAYA POTAPENKO × № 1426-21-80

1970 ◽  
pp. 38-40
Author(s):  
O. O. Kalinina ◽  
O. D. Golyaeva ◽  
O. V. Panfilova ◽  
А. V. Pikunova
Keyword(s):  
Powdery Mildew ◽  
Field Resistance ◽  
Disease Development ◽  
Artificial Infection ◽  
Sources Of Resistance ◽  
Climate Conditions ◽  
High Productivity ◽  
Local Soil ◽  
The Family ◽  
Red Currant

Powdery mildew is one of the most harmful fungal diseases that causes economically significant damage to berry plantations. The disease is common in all areas of currant cultivation in the Russian Federation. In this regard, in modern conditions of intensive berry growing, the problem of breeding cultivars that are highly resistant to diseases and pests becomes urgent. Breeders have a difficult task to combine the adaptive potential of the cultivar with its annual high productivity and resistance to biotic environmental factors. When studying the adaptability of introduced cultivars of red currant and selected forms of the Institute to local soil and climate conditions, the following cultivars were identified as sources of economic and useful characteristics and involved in selection: ‘Belaya Potapenko’ as a complex source of resistance powdery mildew and high marketable and taste qualities of berries; SS 1426-21-80 as a source of high productivity and long racemes (raceme length 11-13 cm; up to 20 berries in the raceme). On their base the selection family of red currant has been developed: Belaya Potapenko × ♂SS 1426-21-80. The study of data on the destruction of hybrid seedlings of the selection family by powdery mildew showed that in epiphytotic conditions, the percentage of intensity of the disease development varies over the periods of screening from 0.2% in May to 20.4% in June. Such indicators served as a prerequisite for conducting a comparative test of breeding material in the field under artificial infection with powdery mildew. After artificial infection on the background of epiphytosis, the rate of intensity of the disease development increased slightly and amounted to 35.6% for the family. There were 30 highly resistant seedlings in the family, 10 of which have remained stable and highly resistant since 2018. In these plants we can assume the presence of the so-called field resistance, controlled by polygens, each of which does not give a visible effect of stability, but with different combinations determines one or another of its degree. Highly resistant seedlings will be used in further breeding studies to identify new sources of resistance to powdery mildew.

Field Performance of a Constructed Litter Trap with Oil and Grease Filter using Low-cost Materials

2018 ◽  
Vol 10 (2) ◽  
Author(s):  
Siti Nazahiyah Rahmat ◽  
◽  
Algheethi Adel Ali Saeed Abduh ◽  
Ahmad Zurisman Mohd Ali ◽  
Mohd Adib Mohammad Razi ◽  
...  
Keyword(s):  
Low Cost ◽  
Field Performance ◽  
Oil And Grease

scholarly journals Morphological and Chemical Factors Related to Western Flower Thrips Resistance in the Ornamental Gladiolus

Plants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1384
Author(s):  
Dinar S. C. Wahyuni ◽  
Young Hae Choi ◽  
Kirsten A. Leiss ◽  
Peter G. L. Klinkhamer
Keyword(s):  
Host Plant ◽  
Plant Resistance ◽  
Host Plant Resistance ◽  
Frankliniella Occidentalis ◽  
Western Flower Thrips ◽  
Resistance Breeding ◽  
Breeding Programs ◽  
Triterpenoid Saponins ◽  
Flower Thrips ◽  
Highly Correlated

Understanding the mechanisms involved in host plant resistance opens the way for improved resistance breeding programs by using the traits involved as markers. Pest management is a major problem in cultivation of ornamentals. Gladiolus (Gladiolus hybridus L.) is an economically important ornamental in the Netherlands. Gladiolus is especially sensitive to attack by western flower thrips (Frankliniella occidentalis (Pergande) (Thysanoptera:Thripidae)). The objective of this study was, therefore, to investigate morphological and chemical markers for resistance breeding to western flower thrips in Gladiolus varieties. We measured thrips damage of 14 Gladiolus varieties in a whole-plant thrips bioassay and related this to morphological traits with a focus on papillae density. Moreover, we studied chemical host plant resistance to using an eco-metabolomic approach comparing the 1H NMR profiles of thrips resistant and susceptible varieties representing a broad range of papillae densities. Thrips damage varied strongly among varieties: the most susceptible variety showed 130 times more damage than the most resistant one. Varieties with low thrips damage had shorter mesophylls and epidermal cells, as well as a higher density of epicuticular papillae. All three traits related to thrips damage were highly correlated with each other. We observed a number of metabolites related to resistance against thrips: two unidentified triterpenoid saponins and the amino acids alanine and threonine. All these compounds were highly correlated amongst each other as well as to the density of papillae. These correlations suggest that papillae are involved in resistance to thrips by producing and/or storing compounds causing thrips resistance. Although it is not possible to distinguish the individual effects of morphological and chemical traits statistically, our results show that papillae density is an easy marker in Gladiolus-breeding programs targeted at increased resistance to thrips.

scholarly journals Genotype-Dependent Tipburn Severity During Lettuce Hydroponic Culture Is Associated with Altered Nutrient Leaf Content

Agronomy ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 616
Author(s):  
Virginia Birlanga ◽  
José Ramón Acosta-Motos ◽  
José Manuel Pérez-Pérez
Keyword(s):  
Low Cost ◽  
Nutrient Content ◽  
Leafy Vegetables ◽  
Production Methods ◽  
Growing Seasons ◽  
Lactuca Sativa L ◽  
Hydroponic Cultivation ◽  
Highly Correlated ◽  
Nutrient Solutions ◽  
Nutrient Traits

Cultivated lettuce (Lactuca sativa L.) is one of the most important leafy vegetables in the world, and most of the production is concentrated in the Mediterranean Basin. Hydroponics has been successfully utilized for lettuce cultivation, which could contribute to the diversification of production methods and the reduction of water consumption and excessive fertilization. We devised a low-cost procedure for closed hydroponic cultivation and easy phenotyping of root and shoot attributes of lettuce. We studied 12 lettuce genotypes of the crisphead and oak-leaf subtypes, which differed on their tipburn resistance, for three growing seasons (Fall, Winter, and Spring). We found interesting genotype × environment (G × E) interactions for some of the studied traits during early growth. By analyzing tipburn incidence and leaf nutrient content, we were able to identify a number of nutrient traits that were highly correlated with cultivar- and genotype-dependent tipburn. Our experimental setup will allow evaluating different lettuce genotypes in defined nutrient solutions to select for tipburn-tolerant and highly productive genotypes that are suitable for hydroponics.

Genetic Diversity, Identification and Utilization of Novel Genetic Resources for Resistance to Meloidogyne incognita in Mulberry (Morus spp.)

Plant Disease ◽  
2021 ◽  
Author(s):  
Gondi S Arunakumar ◽  
Belaghihalli Nanjappa Gnanesh ◽  
Haniyambadi B Manojkumar ◽  
Doss S. Gandhi ◽  
Mogili Thallapally ◽  
...  
Keyword(s):  
Ssr Markers ◽  
Resistance Breeding ◽  
Field Resistance ◽  
Infested Soil ◽  
Root Knot Nematode ◽  
Sources Of Resistance ◽  
Molecular Variance ◽  
Morus Spp ◽  
Principle Coordinate Analysis ◽  
Germplasm Accessions

Mulberry (Morus spp.) is an important crop in the sericulture industry as the leaves constitute the primary feed for the silkworm. The availability of diverse genetic sources of resistance to root- knot nematode (RKN; Meloidogyne spp.) are very scanty and therefore, a set of 415 varied exotic and indigenous germplasm accessions were screened under glasshouse conditions. Twenty one accessions were identified as highly resistant and 48 were resistant, the highest numbers of highly resistant/resistant accessions were found in Morus alba. Further, thirty accessions based on rooting ability were evaluated for field resistance at four different locations with infested soil. Finally, eight germplasm accessions; BR-8, Karanjtoli-1, Hosur-C8, Nagalur Estate, Tippu, Calabresa, Thai Pecah and SRDC-3 were identified as potential genetic sources in RKN resistance breeding programs or as resistant rootstock for the establishment of mulberry gardens. Sixteen SSR markers analyzed among the 77 resistant and susceptible accessions, generated 55 alleles, ranging from 2 to 5 with an average of 3.43 alleles per locus. Principle coordinate analysis grouped the accessions on the basis of RKN susceptible and resistant to a greater extent. The RKN susceptible accessions exhibited higher variability as compared to resistant accessions and they were more dispersed. Analysis of molecular variance showed that maximum molecular variance (78%) within the population and 22% between populations. Results of this study indicate that SSR markers are reliable for assessing genetic variability among the RKN resistant and susceptible mulberry accessions.

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