Arizona republican., 1891-04-17
THE HOP LOUISE.

Impo ortant Facts of Interest to the Hop
 Growing Districts.
 Since the attention of the chronological department of the Oregon Experiment Station has been called to the presence of the hop louse on the Pacific coast every possible effort has been made to determine the best and cheapest way to combat it. Since very thorough work upon this insect has been done by the departments of agriculture in Europe and America contemporaneously (see re- port dept. agr. 1888 p 99) hardly more than corroboration of the results pub lished by the department could be ex- pected here.
 Briefly, the history of the hop louse is as follows: Matched on plum trees in the spring, which trees, by the way, may be long distance from any hop yard; it produces three generations on the plum tree, then flies to the hops and there lives until late summer and aut- umn, increasing with most astonishing rapidity and causing the so-called "blight" so well known to English hop growers. The vines affected look black ened and their leaves are covered with sticky secretion known as "honey dew, !" giving them characteristic sheen. In the summer and autumn, after many generations have been produced on the hops, the last produced returns to the plum and gives birth to wingless fe- males, destined to lay the eggs, which last through the winter, in the bud axis of the plum.
 Visits to hop fields and circular letters have elicited the following important in formation: Individual losses from the hop louse during last season range from SlOO to 5000, depending on the size of the yard and the conditions favorable to the insects rapid increase. The louse has been worse in Washington than in Oregon and only one instance of its oc- currence, in very limited numbers, has been reported from c. lifornia. From the nature of this latter case implicit confidence cannot be placed in the re- port.
 When yards have been infested those more or less shut in by timber, on low lands where but little sun and breeze en- tered were the worst affected, while other yards on higher ground, even though adjoining plum and prune trees, were not affected. The louse has its preferences for particular varieties. For tunately for our hop growers, who would algn Ina Orrn fl 1nac r to affect the Italian prune, and but very few eggs have been found upon cultiva- ted piums or prunes. Even the Dam- son, where one might expect to find them, IS exempt. On the other hand Peterson's Seeding, or Peterson's Drupe, has been found to harbOr many eggs. The Jeffer- son and variety known as the Helen plum also come in for share of favor. Therefore, while it cannot be asserted at this date that cultivated species of prunes are always exempt, 1t would ap- pear from examination of many trees and cuttings that it is the wild plum thickets or seedlings that hop growers should not allow to remain on their premises and which should be entirely removed from hop growing district.
 Many correspondents and others have asserted that they have seen during the past season the hop louse on the willow, on the vine maple, on the alder and even on the oak. In many such cases per sonal examin ations have been possible and the reported hop lice have been | found to be other than Phorodar and have turned out to be species which do not affect hops at all. Others have ridi- culed the tact of the winter eggs being laid on the plum, citing as contradictory | evidence that yards far distant from any plums or prunes have been badly ln- fested. The statement made above that in migrating from plum to hop and from hop to plum the insect may fly or be car ried by the wind long distance answers the attempted refutation.
 Older studies upon this insect, up- on which many hop growers rely for in. formation, has been proven largely in- correct by the more recent work re- ferred to. The supposition that the egg is deposited at the root of the vine in the ground must be done away with. Also the statement, as foolish as it is errone- ous that eggs have been found on a hop root which matched, when warmed, into the genuine mop louse?"
 It is evident from what has been said on the true life history of Phoradon that where hop yard is infested at all, the very best way to insure a chance for i'm munity the following year is to burn the vines immediately after picking. This does not mean two days after picking but at once. Let squad come after the pickers whose duty it IS to burn the vines on the spot even though it takes fuel to accomplish it. This will destroy large proportion of the females and males also before they have flown to the plums Then, by all means, in those sections where the hop interest is paramount, let all unremunerative plum thickets be cut down and burned whether they be near ! by or at distance. This should be done before spring.
 Should the small oval shining black eggs be found on more valuable trees, i.e. plums or prunes, distinguished fromthe egg of the plum aphis not so much, by its size as by its occurrence in far greater numbers than could possibly be the case were it the aphis of the plum, strong caustic sprays might be used in the win ter before the buds begin to swell. This would kill some of the eggs. It should i never he resorted to after the buds be.