Trunk disease management in California

Figure 9

Figure 9 (click for larger view)

The website allows you to display the results in the same type of graph as shown above for Topsin, as well as a range of other graphs and tables.  For example, you can generate a table illustrating the last year that annual net returns are positive (Figure 9).  Adoption of preventative practices can add years to the profitability of a vineyard.  Adopting one of the three preventative practices in year 10 does little to extend the profitable lifespan of the infected vineyard.  Further, when efficacy is only 25% (which may occur in some years, when the climate is ideal for infection of pruning wounds by spores—something you cannot control) and a practice is not adopted until year 10 (something you can control), the vineyard does not generate enough net returns to cover establishment costs.  We can see when adoption occurs in years 3 or 5, however, the profitable lifespan increases, in many cases by nearly twice as much, providing significantly more years of positive annual net returns and positive cumulative net returns for at least some mature age range.

Scenario 2 is a mature vineyard, 10-years-old (Figure 10).  There is a relatively low percentage of vines with symptoms of trunk diseases, approximately 20% of vines in the vineyard.  Because disease incidence can vary according to factors other than vineyard age, disease incidence—in this case, 20%—is the most important factor to consider.

Figure 10

Figure 10

For scenario 2 (mature vineyard, 10-years old where 20% of vines in the vineyard are symptomatic), we recommend you use post-infection practices on the symptomatic vines (Figure 11).  Of the remaining 80% of the vineyard that shows no symptoms, many of these vines may not be infected.  Therefore, it makes sense to use preventative practices on the entire vineyard.  Furthermore, the infections are localized in the wood, and so a symptomatic vine with one dead spur likely has other healthy spurs that should be protected from infection.

Figure 11

Figure 11

 

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