(Partner: New Brunswick Seed Potato Growers Association)
Abstract: In 1997, seed of four potato varieties was greensprouted and planted in replicated 25 foot single row plots at three spacings : 7", 9" and 11". Emergence was measured 18, 24 and 31 days after planting (DAP), and stem counts were taken 43 DAP. The varieties Penta, Russet Norkotah and Shepody were topkilled 70 and 85 DAP and the levels of the common potato viruses PVYo and PLRV were determined using the ELISA sprout test on harvested tubers. The variety Atlantic was harvested at 74, 80 and 86 DAP and Agtron values were measured for chip colour. All potatoes were counted and weighed into numerous size categories depending on end use, including total and marketable. A delay in planting and the development of white sprouts on the control seed pieces resulted in little effect by greensprouting on emergence, stem counts or yields. Virus levels were higher for Penta and Russet Norkotah at the later topkill date. Under these conditions with the variety Atlantic, greensprouting only advanced emergence by a few days and did not affect stem count, specific gravity or yields. It only positively affected chip colour mid August at the closest spacing. There was a yield benefit for all four varieties in the reduction of in-row spacing from 11" to 7".
1Potato and Horticulture Branch, NBDARD, Fredericton, NB E3B 5H1