▁may ▁eventually ▁g ird le ▁the ▁root . ▁The ▁population ▁size ▁of ▁the ▁n emat ode ▁affect s ▁the ▁degree ▁of ▁sympt oms . ▁ ▁Low ▁to ▁moder ate ▁populations ▁may ▁cause ▁no ▁visible ▁above ▁ground ▁sympt oms , ▁while ▁high ▁populations ▁can ▁lead ▁to ▁st un ting , ▁nut ri ent ▁and ▁water ▁def ic ien cies , ▁and ▁event ual ▁die - back ▁of ▁the ▁plant . ▁ ▁On ▁pot ato , ▁in fection ▁of ▁root ▁les ion ▁n emat ode ▁can ▁cause ▁a ▁secondary ▁invasion ▁by ▁Vert ic ill ium ▁dah lia e ▁leading ▁to ▁Pot ato ▁Early ▁D ying . ▁ ▁On ions ▁are ▁another ▁important ▁host ▁of ▁P . ▁pen etr ans . ▁ ▁On ions ▁are ▁an ▁important ▁veget able ▁for ▁consumption ▁in ▁the ▁United ▁States ▁and ▁upon ▁in fection ▁the ▁n emat odes ▁can ▁limit ▁yield ▁and ▁quality ▁of ▁the ▁bul bs . ▁ ▁Pop ulations ▁of ▁more ▁than ▁ 0 . 0 1 ▁n emat ode ▁per ▁cub ic ▁cent imeter ▁of ▁soil ▁resulted ▁in ▁injury ▁to ▁on ions . ▁ ▁There ▁is ▁a ▁negative ▁relationship ▁between ▁the ▁increasing ▁in oc ul um ▁levels ▁on ▁on ion ▁root ▁and ▁top ▁fresh ▁weight ▁at ▁har vest . ▁ ▁L ifecycle ▁ ▁Pr aty len chus ▁pen etr ans ▁is ▁a ▁mig rat ory ▁n emat ode ▁which ▁means ▁it ▁moves ▁from ▁root ▁to ▁root ▁and ▁is ▁also ▁an ▁end op ar as ite ▁which ▁means ▁go ▁into ▁the ▁roots . ▁ ▁There ▁are ▁both ▁female ▁and