How is eutypa dieback typically introduced into vineyards?

• A. Through pruning wounds in moderate temperatures and especially during rain
• B. By wind over long distances
• C. Through irrigation water
• D. By insect vectors

Answer: (A)

Eutypa dieback enters grapevines mainly through fresh pruning wounds when conditions are moist and temperatures are mild. The fungus Eutypa lata releases spores from fruiting bodies on old wood, and rain or wet conditions help these spores reach and infect newly cut surfaces. Once inside, the pathogen colonizes the wood and causes dieback over time. This is why pruning during wet weather or making fresh cuts without protection creates the prime opportunity for infection. Other routes, such as wind spread, irrigation water, or insect vectors, are not the typical entry points for this disease; the critical factor is a moist, moderate-temperature environment that allows spore transmission to a susceptible pruning wound.