Topworking — or topgrafting — to change varieties found unsatisfactory for growing in the avocado orchard at Riverside is used instead of planting a new young tree because a topworked tree comes into production several years sooner and the quality and performance of a new variety can therefore be evaluated earlier. Topworked trees have ranged in age from six to 10 years.

The above progress report is based on Research Project No. 1434.