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The Asparagus Rust; Its Treatment

and Natural Enemies.

BY BYRON D. HALSTED, STATE BOTANIST.

Asparagus-growing is one of the leading industries in several towns in the State; Hazlet, Keyport and Red Bank, in Monmouth county, contain a large number of asparagus farms, from which the product is shipped to the New York market, while Philadelphia is supplied by large growers in Camden, Gloucester and Burlington counties.

Until 1896, the Experiment Station had received but very few complaints of asparagus troubles that were of fungus origin. In August of that year, however, samples of diseased asparagus were brought to the Station, with the statement that the beds were ripening prematurely and the conditions alarming.

It was quickly determined that the source of anxiety was a genuine rust, and in a few days a circular of information was issued, giving some account of the fungus and suggesting measures that might tend to check the development of the trouble the coming year.

Many visits were made to the asparagus regions during the season of 1897; a watch was kept upon the rust as to the time of its development and the forms it assumed, and the injury to the crop recorded. A field of asparagus upon the Station grounds was sprayed at frequent intervals with fungicides, and the results obtained are given in bulletin 129 (June 10, 1898) of the Experiment Station, from which the two plates and some of the matter for this article are taken.

THE ASPARAGUS RUST.

The rust of the asparagus is caused by a fungus that was described by De Candolle as Puccinia asparagi in the year 1805. From this it is seen that the rust upon the asparagus has been known to science for nearly a hundred years. No search of the early writing upon garden

ing has been made for a mention of the trouble, but it is reasonable to suppose that more or less of this fungus has existed beyond the history of man.

Saccardo gives England, France, Germany, Austria, Switzerland, Hungary and Italy. Souauer, Frank, Ludwig, Prillieux and Tubeuf and Smith all make mention of the asparagus rust in such a way as to strengthen the opinion that the parasite is not uncommon in Europe. Zimmermann presents eight figures of the asparagus rust, five of which are from microphotographs, and Plowright gives a description of the three forms of spores. No account of it is met with for Asia or Africa.

The only mention of its being found in the United States previous to 1896 is by Dr. Harkness, and correspondents in California inform us that the rust is not found there at the present time.

It is impossible to account for the unusual outbreak of the rust in the Eastern States in 1896, which, after a full correspondence with botanists, horticulturists and asparagus growers, seemed to be limited in that year to New England, Long Island, New Jersey and Delaware.

The predictions have proved true, and, as a rule, all fields that were badly infested in 1896, in New Jersey at least, were even worse in 1897. A letter of inquiry has been sent to at least one person in each State and Territory, usually a station botanist or horticulturist, and from these reports, kindly furnished, it is gathered that the rust is in the South Atlantic States, including South Carolina, and the large asparagus fields around Charleston in particular. In short, the disease has spread considerably during its second year in this country; but the vast interior and the western part of the United States seem as yet free from the rust.

RECOGNITION OF THE RUST.

When an asparagus field is badly infested with the rust the general appearance is that of an unusually early maturing of the plants. Instead of the healthy green color there is a brown hue, as if insects had sapped the plants or frost destroyed their vitality. Rusted plants, when viewed closely, are found to have the skin of the stems lifted, as if blistered, and within the ruptures of the epidermis the color is brown, as shown in Plate I, Figures a and e.

This brown color is due to multitudes of spores borne upon the tips of fine threads of the fungus, which aggregate at certain points and

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