THE WHITE FLY AND THE REMEDY 



^ I ' HE white fly has proved one of the 

 JL most serious insect pests encountered 

 in the winter forcing of tomatoes, says Mr. 

 Wm. Stuart, of the Vermont Agricultural 

 Experiment Station, in his annual report, 

 which has just reached The Horticulturist. 

 This fly does not succumb to the ordinary 

 remedies such as are employed against red 

 spider, aphis and thrips. This immunity 

 to the ordinary fumigants such as tobacco 

 stems or dust, aphis punk, nicoticide, and 

 sulphur fumes, or to the liquid insecticides 

 applied as a spray, is largely due to the fact 

 that during its immature stages of existence 

 it is less easily destroyed than are the other 

 pests mentioned. The experimental crop 

 was started rather late in the season of 

 1902-03, and hence fewer insects appeared 

 on the young plants than occurred the next 

 year and they were more easily managed. 



Frequent fumigation with nicoticide did 

 not rid the plants of the fly during 1902-03, 

 but kept it from great increase or from 

 actually doing serioiis injury. In 1903-04, 

 however, the plants being started earlier and 

 the insects seemingly more prevalent, fumi- 

 gations with nicoticide seemed to be of slight 

 avail. Trials were made of aphis punk 

 with meagre results. Fir tree oil, lemon oil, 

 X-all and soap solutions were next tried, at 

 strengths in some cases considerably in ex- 

 cess oi those recommended, but with little 

 avail, as the insects seemed to increase rather 

 than decrease. It was decided as a last re- 

 sort to try hydrocyanic acid gas fiunigation. 

 The dose employed was at the rate of 0.2 

 grains of 98 per cent, potassium cyanide to 

 each cubic foot of air space, or at the rate 

 oi. about two-thirds of an ounce to each 



1,000 cubic feet. Fumigation with the dose 

 mentioned destroyed both the nymph and 

 adult forms of the insect and did no injury 

 to the bearing plants. In all cases the room 

 was fumigated in the evening and remained 

 closed until the following morning. This 

 remedy must be handled with creat care. 



In fumigating a second crojD of plants 

 just beginning to blossom and set fruit, it 

 was thought best because of the tenderness 

 of the plants to use a weaker dose, the 

 amount being cut down to about .014 grams 

 potassium cyanide per cubic foot, or 50 

 grams to the room. Notwithstanding this 

 very material decrease in amount of cyanide 

 used, considerable injury was done, for the 

 most part confined to the tender growing 

 snoots and blossoms. This outcome seems 

 in part due to the higher temperature of the 

 house during the fumigation, it having stood 

 at 70 degrees F. instead of 60-65 degrees as 

 at the first treatment. This tendency to in- 

 jury in high temperature fumigations is cor- 

 roborative of observations made by others. 

 Subsequent trials with the same strength at 

 lower temperatures did no injury to the 

 plants, yet destroyed the insects. 



Cucumbers, lettuce and a mixed lot of 

 plants have been fumigated in the same man- 

 ner as just outlined w'ith equal satisfaction. 

 Fumigation with light doses, half ounce per 

 1,000 cubic feet of air space, at temperatures 

 not over 60-65 degrees F. and long expo- 

 sures is efifective, and, in the hands of the 

 ordinary person, is perhaps on the whole 

 more satisfactory than strong doses and 

 short exposures as a remedy against the 

 white fly. 



Peas which have been eaten by the weevil 

 may grow, as the insect does not always in- 

 jure the germ. The plant, however, will 

 be less thrifty, because it should get a good 

 start from the seed, which it cannot get from 

 a half eaten seed. Better feed such peas 

 to the chickens and sow perfect seed. 



Damping ofif of hot-bed melons is caused 

 by closing the hot-bed too soon after water- 

 ing, especially on warm days. The cells 

 at the surface of the ground become injured 

 and a fungous disease called damping oflF is 

 induced. Admit fresh air and apply air 

 slacked lime. 



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