Topics in Subtropics

A sure way to generate controversy among citrus growers is to initiate a discussion on navel orange tree pruning. Some growers maintain that yield and fruit size is best maintained by minimal pruning, while others believe that the number of large fruit is increased when trees are severely pruned.

"We don't need to irrigate, it's winter." This is a commonly held idea, and many years it is true. Adequately timed rains will often meet the needs of avocado trees during the winter period, and in times like last year, even satisfy much of the spring requirement.

There have been a lot of new avocado orchards planted during the last few years. These often have been in old Valencia orchards or lemons that had poor production. In order to save money, growers have just cut the trees at ground level and replanted the avocados near the stumps.

Many citrus trees in the southern end of the San Joaquin Valley are grown on moderately calcareous soils and frequently have high levels of boron in the leaf tissue. Citrus is sensitive to boron. Boron, when excessive, may cause defoliation and significant yield loss.

While both horseweed and hairy fleabane have been here since farming began in the region, its only since about 2003 that they have become such an obvious problem, particularly in tree and vine systems and non-crop areas.