Scab control

Schwabe, W.F.S., and Jones, A.L. 1983. Apple scab control with bitertanol as influenced by adjuvant addition. Plant Dis. 67 1371-1373. 

Davis, J.G., Callihan, R.H., Effects of gypsum, sulfur, terractor, and terractor super-x for potato scab control. Am Pot J 1974 51 35-43. 

MILLS OR RiMPRO For decades the Mills scab table was considered to be the most important tool for calculation of infections. Large numbers of unsuccessful attempts at scab control, however, have cast doubt on the accuracy of this table, which only takes into account the physical factors relevant for infection. It ignores the biological factors (e.g. spore potential, spore maturity, leaf growth), and it is questionable whether the calculations are correct. 

DIRECT. Scab is the most important disease in fruit production, and more than half of the measures required are for the purpose of scab control. Unlike animal pests, scab is an invisible enemy , which does not become visible until the fruit tree is already infected. For this reason all treatments must be performed before an infection. 

Successful scab control cannot be achieved unless all the people involved (growers, extension officers, etc.) act with the utmost flexibility. For the grower this means spraying more frequently (twice a week if necessary) at times when there is a risk of scab, and reducing spraying frequency at times when there is no scab risk. 

Niacide [FMC], TM for fungicidal products containing dimethyl dithiocarbamates used mainly for scab control. 

Such situations arose many years after commercial Introduction In the cases of Dodlne for apple scab control, Kltazin P for rice blast control, and benomyl for eyespot control In cereals. However, negative findings in glasshouse and field experiments at least indicate that a build-up of resistance is unlikely to happen quickly, so that there is more time left for development and implementation of antiresistance strategies. 

Other materials based on EDA have also been suggested as fungicides. The most important of the imida2oline type (162) is 2-heptadecyl-2-imida2oline (163), prepared from EDA and stearic acid [57-11-4]. It is used as the acetate salt for control of apple scab and cherry leaf spot. A 2 1 EDA—copper sulfate complex has been suggested for control of aquatic fungi (164). 

Mepanipyrim is a nonsystemic fungicide to control gray mould on vines, tomatoes, etc., and scabs on pome fruits. 

Control of melanose and scab is a standardized procedure in Florida, using the so-called neutral or insoluble copper materials at low poundage to reduce the scale problem. In both Argentina and Brazil, these diseases are very important—including sweet orange scab, not known in Florida—but generally must be controlled with Bordeaux because of the inability to import the newer materials. In the drier areas, these diseases are not so important. 

Lime Add to cabbage family section to control clubroot, in the fall before planting, but only if necessary to raise pH, not routinely. Do not lime when growing potatoes, as it can encourage scab. 

On zinc phosphate conversion coatings, the "Mannich" derivatives of poly-4-vinylphenol have demonstrated performance equivalent to chromic chromate systems in salt spray, humidity, and physical testing. In addition. Table III illustrates results observed with automotive body paint systems evaluated by the "scab" or "cycle" test which causes failure more typical of actual end use conditions than do salt spray evaluations. Again, results equivalent to chromic-chromate post-treatments were obtained. In addition, the humidity resistance and adhesion tests were essentially equivalent to the chromium controls. 

All rats survived dermal doses of up to 60 mg/rat administered over 13 weeks. Mean body weights were up to 14% lower than controls, and redness, scabs, and ulceration occurred at the application site. In mice, applications of up to lOmg/mouse produced increased liver and kidney weights. Compound-related skin lesions included sebaceous gland hyperplasia and hyperplasia and hyperkeratosis of the stratified squamous epithelium at the site of application ovarian atrophy was also considered to be compound related. 

I thought it best to control the flows of nitrogen, natural gas, and air, myself. Basically, the other scabs on the sulfur plant were head office people, whom I did not trust. The reheat phase of the start-up seemed to be going quite slowly. The combustion chamber temperature crept up by 50°F an hour, rather than the normal 150°F per hour. To speed the reheat, I reduced the nitrogen flow. This helped, but not by much. 

Triazole derivatives of the dichlobutrazole and paclobutrazole types are closely related chemically to the triazolyl-0,N-acetals previously mentioned. The oxygen atom of the acetal function was merely replaced by a methylene group. Dichlobutrazole (ICI) was developed for the control of powdery mildew, rust and scab in cereals. Paclobutrazole is under development as a growth regulator. 

Paul, V., and Brandes, W. (1983) Scanning Electron Microscopy Studies on the Pathogensis of Apple Scab and its Control with Baycor, Pflanzenschutz-Nachrichten Bayer 36, 21 - 37. 

When the EBI fungicides are applied later than 72-96 hours after the beginning of the scab infection period but before symptoms are visible, chlorotic spots or flecks with few or no conidia are produced in place of typical sporulating lesions (Figure 2). This is referred to as presymptom control by Szkolnik (23) and it is a form of post-infection or curative action. Dodine and benomyl are examples of fungicides with presymptom activity. Presymptom activity becomes more obvious as the time of application increases beyond the 72-96 hour after-infection period. In greenhouse trials, sprays of bltertanol, etaconazole, fenarimol and triforine reduced conidial production 85 to 99% when applied five days after inoculation (20). 

Presymptom activity has also been observed in field trials. If sprays are delayed late into the incubation period, presymptom control can be increased by applying a second spray seven days after the first application (12). There are indications that chlorotic lesions will not produce conidia after the use of EBI fungicides is discontinued (6). However, the viability of the fungus in these lesions is influenced by moisture, dosage of fungicide, timing, and other factors. In one trial, the scab fungus was isolated from chlorotic lesions in leaves (12). 

Because of their after-infection and antisporulation activity against scab, the EBI fungicides are especially suitable for use in predictive disease control programs. Predictive disease control is an important part of integrated pest management programs on apples. A predictive system means control measures are applied after the onset of infection. Small special purpose computers with field... 

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