PRELIMINARY NOTES ON POTATO LEAF-HOPPER 13 
PAGE SpleELDy PLAN AND RESULTS OF _POTATO: SPRAYING 
EXPERIMENTS ON ONE-ACRE PLOTS AT GRISWOLD 
FARM, MINNESOTA 
No. and date Yield in bu. 
Variety _of applications Materials le) pemacre 
Bliss Triumph I-June 29 | Liquid bordeaux mixture 4-4-50 
2-July 14 and lead arsenate 2-50.......... 273 
3-July 27 
4-Aug. 18 
Bliss Triumph As above Liquid bordeaux mixture 4-4-50 
and Black Leaf 40, 1-800 and 
leadvarsenater2=50n osc tsa mentos: 337 
Bliss Triumph 1-June 30 | Dosch 13-8-79; copper calcium 
2-July 14 ARSeNaLew GtShs .ccratcoarow se eae 185* 
3-July 27 ~ 
4-Aug. 18 
Bliss Triumph As above Dosch 13-8-79; copper calcium ar- | 
senate dust and Dosch 2-4% 
Micotime Mller usta. sien eee «> 201* 
Bliss Triumph I-June 2 Inter-series check, between dusted 
2-July 14 and sprayed series, lead arsenate 
. 3-July 2 PIAA Aes HEA IC Beto 193 
4-Aug. 18 
Bliss Triumph 1-June 30 | Isolated check, lead arsenate, paris 
2-July 14 Sreeme Mime 7-1-40ee sos. wel: 152* 
Se 3Iuly 27 
4-Aug. 18 
* Yields slightly influenced by outbreaks of Colorado Potato Beetle. 
Liquid bordeaux mixture markedly decreased the number of leaf- 
hoppers and the percentage of foliage injury in both varieties. The 
addition of nicotine was followed by a greater decrease in the number 
of hoppers, but additional lessening of foliage injury was only notice- 
able in the early variety. In the dusted plots, the number of hoppers 
and the injury were lessened, but these decreases were not so con- 
sistent as in sprayed plots and require further experimental evidence. 
Nicotine used alone, in dust or liquid form, produced small decreases 
in both number of insects and injury. 
It will be seen that liquid bordeaux mixture gave good control 
against the leaf-hopper in every plot where it was applied, the yield 
being decidedly better than in the check and dust applications. In the 
tenth-acre plots no advantage was gained by adding the nicotine solu- 
