Venturia inaequalis

Apples Scab Venturia inaequalis Bordeaux mixture... 

Larbi M, Gobat JM, Fuchs JG (2006) Inhibition of the apple scab pathogen venturia inaequalis and the grapewine downy mildew pathogen plasmopara viticola by extracts of green waste compost. ORBIT Conference... 

Sulfur sprays More severe apple scab Venturia inaequalis), similar orange tortrix Argyrotaenia citrana) Vossen et ai. (1994)... 

In apple, the glycoside phloridzin (1.27) and its aglycone phloretin are thought to inhibit the apple scab fungus Venturia inaequalis. Phloridzin is also an ort/20-dihydroxyphenolic compound, and, like chlorogenic acid, can also be easily converted to a reactive quinone upon attack by a pathogen. Raa (1968) demonstrated that oxidation products of phloridzin inhibit fungal... 

Raa, J., 1968, Polyphenols and natural resistance of apple leaves against Venturia inaequalis, Eur. J. PlantPath.74 37-45. 

Influence of Bitertanol on the Pathogenesis of Venturia inaequalis (Apple Scab). Apple scab is the most serious disease of apples and... 

Paul, V. (1981) Biology of Venturia inaequalis (Cooke) Winter, the Pathogen of Apple Scab, Pflanzenschutz-Nachrichten Bayer 34, 60 - 74. 

Figure 1. A germinated conidium of Venturia inaequalis on a apple leaf treated with fenarimol 12 hours before inoculation and incubated in a moist chamber for 23 hours after inoculation. Bar 1 micron.

Hoch, H.C., and Szkolnik, M. 1979. Viability of Venturia inaequalis in chlorotic flecks resulting from fungicide application to infected Malus leaves. Phytopathology 69 456-462. 

Szkolnik, M., and Gilpatrick, J.D. 1969. Apparent resistance of Venturia inaequalis to dodine in New York apple orchards. Plant Dis. Rep. 53 861-864. 

A basic principle in plant pathology is that fungicides are used for crops that lack natural resistance to the fungus involved. Two notorious examples are Phytophthora infestans on potato and Venturia inaequalis on apple. ISfo farmer would go to the labor and expense to spray his potatoes or his apples if he could have plants that successfully fight off their fungi. This principle says further that the amount of fungicide needed or the frequency of application is inversely proportional to natural resistance. 

Sensitivities (ED50) of 200 monoconidial isolates of Venturia inaequalis to the sterol demethylation inhibitor flusilazole (38) were determined, based on the inhibitory effect on mycelial growth [96]. 

Rollinger, J. M. Spitaler, R. Menz, M. Marschall, K. Zelger, R. Ellmerer, E. P. Schneider, P. Stuppner, H., Venturia inaequalis-inhibiting Diels-Alder adducts from Moms root bark, J. Agric. Food Chem., 2006, 54, 8432-8436. 

No problems in the field performance of DMIs have been observed yet for the control of apple scab, although strains of Venturia inaequalis with reduced sensitivity to DMIs have been observed in a few field plots. 

Tolkmith (1966) developed the active substance 0,0-diethyl phthalimidophos-phonothioate (ditalimfos 36), which is a very effective fungicide against powdery mildew in apple and cherry orchards, cucumbers and roses, and is also effective against apple scab ( Venturia inaequalis) and diseases caused by Monilia fructicola, etc. (Huisman, 1972 Huisman and Peskett, 1973). In addition to its protective effect ditalimfos also has a curative action, and is virtually nontoxic to warm-blooded organisms. 

Fortunately, already within the currently known examples, important differences in the dynamics of resistance spread and concurrently in the practical consequences can be found. Worst-case examples, represented by pathogens such as cereal powdery mildew or Septoria tritici, are characterized by a rapid spread of resistance within the fungal population over continent-wide distances but are obviously rare. In other cases such as with the apple scab pathogen (Venturia inaequalis), problems remain localized to certain regions or even individual orchards for many years and give a good chance for consequent resistance management. 

Dodine 10 Apple scab Venturia inaequalis Medium... 

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