late sowings were made, or where large quantities of manure have been applied to the land just previous to planting. These practices result in an over-production of tops which die late in the season affording an excellent opportunity for infection thru the dying necks. The bulbs from such plants are usually small and soft, and later show a high percentage of rot in storage.

SOIL TYPES.

Early in the study of this disease it was believed that the fungus was more prevalent in the muck soils, since muck onions showed a comparatively larger amount of rot. It was found, however, that the amount of neck rot depended largely upon other factors, mainly degree of maturity of bulbs, extent of curing and the weather at curing time, and the storage conditions under which the onions were placed. Upland onions often die and dry down earlier in the season, and the bulbs are often firmer as a result. A number of instances have been noted where red onions growing upon upland of a loamy character have shown considerable neck rot in storage. One instance came to the writer's attention where the sclerotia of the fungus were found upon the bulbs grown upon a loamy soil, at the time of placing them in the storage house in early fall. None of the onion growing regions visited by the writer were found to be entirely free from the neck-rot disease.

AIR DRAINAGE.

Air drainage of the onion fields appears to be an important factor. One small onion-growing section was studied in particular since it had the reputation of consistently yielding onions which later developed considerable neck rot in storage. The factors at work here were plainly the high hills and dense woodland on two sides. of the onion fields. The dews and rains did not evaporate readily and the crop remained wet during the greater part of the forenoon. This is especially detrimental during the harvesting and curing periods.

STORAGE CONDITIONS.

Careful investigations have shown that of all the various factors considered which have a bearing upon the development of the neckrot disease, the control of storage conditions is the most important.

The factors which favor onion neck rot are overheating and poor ventilation in storage houses. It must be admitted, however, that the very best houses cannot carry a crop safely thru the storage season when the bulbs are soft and poorly cured, and moist weather prevails soon after storage begins. A considerable number of the houses used for onion storage are entirely unsuited for this purpose. One particular storage house, having a capacity of approximately 20,000 crates and in which several thousand crates were lost thru neck rot in 1915, was visited by the writer for the purpose of securing some data as to the relative humidity of the house. This house was of concrete construction. It had a rather low, flat roof, only three or four doors along each side of the building and very meager provisions for ventilation thru the roof. The house has single walls and is heated by steam, the pipes running along the outside walls. As cold weather came on and steam was passed thru the heating system it vaporized all the frost on the walls and pipes, the moisture passing thrucut the stored onions bringing on a considerable amount of neck rot in the course of a few days.

Ventilation is of prime importance. The roof should be of a steep pitch, and preferably double, to draw out the moist air. The proper regulation of the ventilation vents is important. These should be closed during damp, foggy, misty weather. The writer traced a severe epidemic of neck rot in one storage house to the fact that the owner opened the doors and left them open during a warm, misty day in mid-winter while a carload of onions was being sacked and removed from the storage house.

Records of the temperature and humidity in onion storage houses were obtained by the use of carefully adjusted Lambrecht polymeters. These records show that a relative humidity of 65-70 per ct. coupled with a temperature of 16-22° C. is very detrimental to onions in storage.

A study of the temperature relations of the fungus show that the temperature of the storage house must be kept very close to 0° C., or about 34° F., in order to prevent the development of the neck-rot fungus. Ames (1915) has shown that a temperature of near zero Centigrade (32° F.) must be maintained to prevent the development of rot fungi in refrigerating experiments.

The onion storage house at South Lima, New York, operated by Mr. C. C. Mowris, was placed at the writer's disposal for the purpose of storage observations. Very little neck rot occurred here. This house, which is one of the best, shows a very desirable type of construction providing ample means for ventilation and heating (Plate XXIX, fig. 2).

STORAGE EXPERIMENTS.

Occasionally one finds notices posted on onion warehouses to the effect that no onions having necks or stems longer than one and one-half or two inches will be accepted." Because of the fact that some onion buyers lay particular stress on the length of neck of onions for storage, claiming that long-necked onions do not keep as well as the short-necked ones, some tests were made upon this point. On September 24, 1913, the writer visited a field in which some neck rot had occurred the previous season, and also during the present season, in crates of onions then in windrows. Six crates of these onions were prepared for an experiment. In two the bulbs were topped very short; in two they had necks 3-4 inches long; while in the remaining two the tops were left uncut. Three of the crates (one of each pair) were stored in a very dry, cool place (the loft of a large building). The other three were stored in the rather damp basement of a storage house where the ventilation was very inadequate tho similar to that of some onion storage houses. These two lots of onions were kept in these storage places until March 20, 1914, and data secured from time to time as to the number of bulbs affected with neck rot. A summary of the data shows that an average of approximately 45 per ct. of the bulbs in the damp storage were destroyed by the neck-rot fungus and the remainder sprouted. Of the bulbs in the very dry storage between 2 and 3 per ct. were destroyed by the neck-rot fungus while only a few bulbs sprouted. As to the effect of short versus long topping and tops uncut upon the amount of neck rot no data could be secured since all were rotted alike in the damp storage. In these experiments the length of neck did not appear to be an important factor, the humidity of the storage place being the factor which influenced keeping quality.

A similar experiment with mildewed onions was carried along with the above-mentioned series and as with the normal crop onions

the length of neck proved unimportant; the humidity of the storage quarters determined the keeping quality. The mildewed onions showed neck rot quicker in the damp storage than did the normal crop. It was evident that the mildewed crop was not as mature and carried more moisture into the storage with it.

The results of these experiments indicate that the length of neck, whether one or three inches long, has no relation to the amount of neck rot.

In an attempt to determine how soon after being placed in storage the neck rot would appear upon the onion bulbs, an experiment was conducted in which thoroly ripe and immature bulbs were compared. On September 3, 1913, crates of ripe and of immature onions were taken from windrows in an onion field in Livingston County, New York, and immediately transported to an onion storage-house in which considerable neck rot had occurred the previous season. On September 24, or 21 days later, the neck-rot fungus could be found fruiting on a considerable number (about 10 per ct.) of the bulbs in this rather damp storage house even tho the bulbs were in new crates not used for onions before. The immature bulbs showed a greater development of the disease.

These and similar storage experiments emphasize two important points; namely, that the crop must be dry and mature and stored in a dry, well ventilated house in order to materially check the development of the neck-rot fungus.

STUDY OF REMEDIAL MEASURES.
SPRAYING.

As to the effect of spraying onions with bordeaux mixture upon the amount of neck rot which developed in storage the writer has the following data to offer. Thru the courtesy and cooperation of Mr. Henry Greffrath of South Lima, N. Y., the crops from two fields of onions, one sprayed with bordeaux mixture, the other unsprayed, were placed in storage and when the stock was sold at the end of the storage period observations were made on the amount of shrinkage, due mainly to neck rot and sprouting. The data are as follows: 2315 bushels unsprayed onions sold March 1, 1914, gave 15.2 per ct. shrinkage; 942 bushels sprayed onions sold April 8, 1914, gave 10.8 per ct. shrinkage, a gain of 4.4 per ct. due to spraying three times with 5-5-50 bordeaux mixture. It is to be noted, however, that the

sprayed onions were removed from the storage over one month later than the unsprayed crop. It is also worthy of note that the sprayed stock was topped by a topping machine while most of the unsprayed stock was hand topped. Attention has already been called to the fact that many onion growers claim that hand-topped onions will keep better than machine-topped stock. It may be well to state that both lots of onions were stored in the same storage house and under the same conditions and that the storage was slightly overloaded which is very unfavorable to long keeping.

The spraying outfit used by Mr. Greffrath was one designed by himself for the purpose of spraying celery and onions. It consisted of a boom carrying fourteen nozzles eighteen inches apart, attached to a field power sprayer by two leads of hose. The sprayer is driven. along the alleys, which usually consist of two rows of celery or lettuce between wide strips of onions, and the boom is carried by two men over the onion rows. No resin sticker was used in the bordeaux mixture since it was found that by going over the rows twice, i. e., once each way after short intervals of time, carrying the boom with the nozzles pointed slightly forward, and using high pressure (200 lbs.), the onion foliage could be completely covered by the fine, mist-like spray.

In a series of smaller experiments conducted at the Geneva Station, in which no data as to yield were secured, it was found that for a combination spray for onion mildew, neck rot and thrips, 5-5-50 bordeaux mixture to which were added Black Leaf 40 at the rate of three-fourths pint to 100 gallons of the spray mixture, and soap at the rate of 5 pounds per 100 gallons could be used with comparative safety on onions. A very slight discoloration of the leaves occurred where the mixture collected in drops. The nicotine extract in the mixture appeared to be quite effective against the thrips. There are several serious difficulties met with in the spraying of onions which tend to make onion spraying very unpopular among onion growers. The most important of these difficulties is the tendency of the tops of the plants to drop over and become entangled just at the period when fungus diseases appear, making it very difficult to pass thru the field. Also on account of the glaucous character of the onion leaves, it is very difficult to make the spray stick to the foliage when using one of the low-pressure outfits even when the resin sticker is added.