Yield Loss in Garlic Caused by Leek yellow stripe virus Argentinean Isolate.

Garlic plants (Allium sativum) are naturally infected by a complex of viruses in the genera Potyvirus, Carlavirus, and Allexivirus. The yield of virus-free garlic plants (noninoculated control) was compared with that of plants infected with an Argentinean isolate of Leek yellow stripe virus (LYSV; L treatment) and garlic plants infected with the virus complex (VC). Evaluations were conducted in the field and in anti-aphid cages during two crop cycles after planting three sizes of cloves (categories). The percent plant emergence in the noninoculated control and in the L treatments (between 80 and 100%) did not differ statistically, but the percent emergence for these two treatments was double that for the VC treatment (25 to 62%). Plant height and leaf number in the L treatment were lower than in the noninoculated control during the first evaluation (year 1), but they did not differ during the second evaluation (year 2). However, both treatments produced taller plants with more leaves than those of VC in both years. The L treatment decreased bulb weight up to 28% and perimeter up to 9% when compared with those in the noninoculated control maintained in the anti-aphid cages until the end of the experiment. However, differences between these treatments were higher in the field experiments where plants were exposed to infection by other viruses (up to 36% in bulb weight and 13% in perimeter). Bulbs of the VC-infected plant treatment were reduced up to 74% in weight and 37% in perimeter. In field evaluations, a high percentage of plants were infected with Onion yellow dwarf virus (58 to 100%), whereas fewer were infected with LYSV (15 to 68%). Garlic virus A infection was high in plants previously infected with LYSV (96 and 97%), but lower in the noninoculated control (12 and 68%). These results show the high impact of the virus complex on garlic yield and the effect of LYSV as a component of the garlic virus complex.