Sulfur dust

Sulfur has long been known for its properties as a pesticide and a curative agent. Homer spoke of the pest-averting sulfur as far back as 800—1000 BC, Hippocrates (400 Bc) considered sulfur sa an antidote against plague, and Dioscorides (100 ad) used sulfur ointment in dermatology (244). In 1803, the use of a lime—sulfur protective treatment for fmit trees was reported, and in 1850 sulfur dust was used to protect foHage (245). In 1891 sulfur dust was used on soil to control onion smut (246). 

In addition to the tests made on peaches and apricots, samples of prunes from trees that had been sprayed with parathion, DDT, DDD, basic lead arsenate, and toxaphene at the rate of from 1 to 2 pounds of these insecticides per 100 gallons of water were tested on larvae of Aedes aegypti. The trees had been sprayed on April 20 and June 16, 1948. The fruit was harvested on or about September 10. Prunes from trees that had been treated with 1 quart of tetraethyl pyrophosphate and 12 pounds of sulfur dust per acre on June 15, and harvested about July 6, were tested on larvae of the above named species. None of the prune samples tested in this study exhibited any significant toxicity to mosquito larvae as compared with the unsprayed check. 

In 1875 Pollacci (7) reported grape leaves treated with sulfur produced hydrogen sulfide gas. Recently it has been reported that hydrogen sulfide gas is produced by sulfur-dusted lemons and oranges (22). This gas which emanates from sulfured plants is also produced by the reactions of ingredients in the widely used lime-sulfur sprays. St. John and Groves (9) have excellently reviewed the chemistry of these mixtures. 

Atmospheric oxygen appears to accelerate hydrogen sulfide and sulfur dioxide formation by sulfur-dusted lemons. An experiment in which lemons were incubated in a bottle which was opened hourly during the day yielded more hydrogen sulfide and more sulfur dioxide than when the bottle was kept closed at night, though the entire experiment was conducted in the dark (18). 

Under natural growing conditions, only lemon fruit and leaves that are exposed to direct sunlight are injured by sulfur dust. The question then arises as to what factors raise the temperature of the plant parts sufficiently to cause volatilization of sulfur and injury at one time and not at another (18). 

In desert areas of southern California fruit are often injured but leaves are seldom injured by sulfur dust. In coastal areas fruit burn is less marked but leaf burn may be acute. Where the air-vapor density is high, leaf temperatures in the sun may sometimes become higher than fruit temperatures. The leaf, a better absorber of radiation and a better radiator than the fruit, has a higher surface-mass ratio and appears to be very sensitive to the heat trap effect of high vapor density its temperature changes with great rapidity, but fruit temperature may lag until the danger period is passed (18). 

The radioactivity of the hydrogen sulfide produced by 28 lemons treated with radioactive elemental sulfur dust, 28 lemons treated with radioactive sulfur dioxide gas, and 28 lemons treated with a radioactive sulfuric acid solution is expressed as per cent specific activity (Table II), which for the purpose of this report is defined as ... 

Table II shows that 100% of the hydrogen sulfide produced by sulfur -dusted fruit was derived from the sulfur applied, 11% from the sulfur dioxide treated fruit, and 5% from the sulfuric acid treated fruit. Thus, the higher the state of oxidation of the sulfur applied, the more limited the production of radioactive hydrogen sulfide. No hydrogen sulfide was obtained from the controls.

The alkali-soluble protein of the peel of lemons treated with hydrogen sulfide, sulfur dioxide, and sulfuric acid contained radioactive sulfur, but the fruit treated with hydrogen sulfide had a significantly lower per cent specific activity in the alkali-soluble protein fraction than did the sulfur dioxide or sulfuric acid treated fruits (Table VII). These results suggest that sulfur dioxide and sulfuric acid react with protein more directly, while hydrogen sulfide perhaps must be oxidized first, as indicated in Table III. It also appears (from Table VII) that the alkali-soluble protein may have been dismuted as the amounts isolated were less in both the hydrogen sulfide and sulfur dioxide treated fruit than in the incubated or nonincubated controls. Other evidence of dismutation has been obtained in experiments where incubation at 60° C. was accompanied by the production of free ammonia (18), and the recovery of free ammonia and six amino acids in the exudates of incubated and sulfur-dusted fruits (18). 

Sulfur dust has a very low minimum ignition energy (3 mJ), so particular care is necessary in formulating protective measures. 

The first was the rapid spread of Uncinula necator, vine powdery mildew, following its identification in England in 1845. A search for control methods led, from the initial observation by Mr Tuker in England that sulfur was an effective treatment, to the development in 1855 by Bequerel of a fungicide application programme based on the use of a fine form of sulfur dust. 

Inorganics Sulfur dust and sprays, diatomaceous earth, micronutrients (Si orZn), iron phosphate, CO2, N, copper hydroxide, Bordeaux mixture Common In some countries Common... 

At the end of the fermentation the wine will be turbid and muddy from the suspended yeast cells and the debris from the fruit. Most of this material will settle quickly, forming a more or less thick layer in the bottom of the bottle. The new wine should be syphoned away from the deposited sediment promptly to avoid off flavors from autolysis of the yeast in the sediment. Also at this time wine acquires the defect of H2S which is produced by reduction of the elemental sulfur dust applied to the grapes as fungicide by the decomposing yeast cells in the thick layer of sediment. The first transfer of the new wine from the sediment should occur very soon after active fermentation, the second about two weeks later, and the third and possibly a fourth two to six months later. These rackings may be conducted under a blanket of nitrogen or carbon dioxide if the particular wine oxidizes easily. 

Sulfur-Based Pesticides. Sulfur (elemental) has been used as an effective acaricide, fungicide, and insecticide. For ease of use, a number of special formulations are available, ranging from sulfur dusts (up to 95% sulfur) a wettable powder (30 to 90%) and paste-like solutions in which the sulfur is ground to a fine colloidal form. Such formulations may contain up to 50% sulfur. Target plant diseases of sulfur when used as a fungicide include apple scab, brown rot. downy and powdery mildew, and peach scab. Against insects, sulfur is effective for mite, scale, and tJirip. Most formulations are not injurious to honeybees. 

A consultant s website reports a helicopter crash apaprently caused by insufficient cleaning of a tank between sulfur-dusting and permanganate application. Mixtures of the solids may ignite on modest friction [Editor s experience]. 

Nontarget Effects. The shift from sulfur dusting to Bayleton spraying in California appears to be associated with an increase in predatory mite populations, which were uncommon in vineyards on sulfur programs (personal communication). On the other hand, pestiferous Erineum mites and thrips appear to increase where sulfur usage has been reduced, although a clear cause and effect relationship has not been established. 

Although all sulfur is produced—and most is consumed—in a molten state, the preponderance of international commerce takes place in solid form. Vancouver, Canada, is the world s leading sulfur-exporting port, with 2004 volumes of 6.3 millions tons, all solid. Sulfur is solidified into a variety of forms, which will be discussed in the following section. Formed solid sulfur is easily transported by truck or railcar but caution must be exercised in order to avoid fugitive dust and spillage. Sulfur dust is highly visible, corrosive, and, under certain circumstances, explosive. In the... 

Fruit covered with a powdery w hite coating. Cause Powdery mildew. This fungal disease, most common on red raspberries, makes fruit inedible and may weaken or kill whole canes. Pruning out old canes to provide good air circulation aids control. To prevent the disease, apply sulfur dusts. To control e.xisting infection, apply lime-sulfur spray. Resistant cultivars... 

Rotenone-bearing preparations Rotenone concentrates Sheep dips, chemical Sodium arsenite (formulated) Soil conditioners Sulfur dust (insecticide) Thiocyanates, organic (formulated)... 

Position of sulfur nozzles. For best results, the spray nozzle header is located parallel to the axis of the sulfur-coating drum. The nozzles in the header are 8 in. apart on centerline. The header is located so each nozzle is spraying vertically down 4% in. onto the fastest moving section of the rolling bed. If the nozzles are placed farther away, the sulfur dust loading in the drum is increased and the quality of the product is decreased. Increasing the spray distance beyond about 8 in. from the bed is both impractical and hazardous as sulfur explosions may occur if... 

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