COME SEPTEMBER-

September never lets us down, and this one was no exception. How much rain has fallen across the Valley? It all depends on location. I think it safe to say a minimum of five inches has fallen everywhere, and some locations got that much and more the last Sunday in September.

Not only that, the season's first cool front came in last week. Though temperatures did not drop enough to constitute an "official" cold front, it was refreshing to have a northwesterly breeze (breeze, not strong winds), sparkling blue skies and milder temperatures for a couple of days.

Rainfall upstream has not apparently been as productive in terms of putting more water into the lakes. The US share of waters is currently around 72 percent of conservation level, not much changed from a month ago. Mexico's share of waters has, however, increased from the low to mid 30's to nearly 40 percent of conservation level.

NEW SEASON-

The new crop is ready to go, as quite a few orchards are passing maturity tests?even with the heavy rains. The rains have likely delayed the startup of harvesting due to extremely wet fields, but I should think there are orchards dry enough now for harvesting operations.

What's the new crop like? Indications are that there will be more of it and that fruit size may be as good as last year. Some are predicting a substantial increase of up to 20 percent more, but others don't think there's quite that much out there.

Undoubtedly, there will be the usual plethora of blemishes and scars on the fruit, as there is just no getting away from our winds. However, citrus rust mite blemishing should be minimal, as this pest just didn't like the weather we had (up until September). Still, it is no time to let your guard down, as the mild, rainy weather can trigger a population increase that could readily result in significant damage in the next month or so.

CROP ESTIMATES-

The official crop estimates will be announced by USDA on Thursday, October 12, at 7:30 in the morning (CDT). Because of widely divergent early estimates in Florida, there is a bit more interest than usual in this USDA estimate. To recall, Elizabeth Steger says less than 130 million boxes of oranges in Florida; Louis Dreyfus claims about 160 million, while some growers were looking for more optimistic levels. Those were August estimates, and FCOJ futures prices are still declining from the resulting August highs of about $1.85, with the latest close near $1.70.

For Texas, some are reportedly calling for an increase of as much as 15-20 percent in grapefruit, with more modest increases (10 percent or less) in oranges. Meanwhile, it was recently announced that California's navel crop is expected to be down about one-fourth from last season, with shipping to start a little later in November. Too, California Valencias are getting scarce, so mid-October could see a shortage of California citrus.

ABOUT FRUIT SIZE-

Opinions differ as to the potential fruit size of the current grapefruit crop, with some calling for generally larger sizes such as occurred last season; and others contending that the fruit cannot achieve last year's size levels because of the overall increased fruit set.

As a rule, with more or less normal growth and development and mature trees, the relative size distribution of fruit is not significantly affected by small differences in annual production. That is to say that the percentage of any given size of fruit will be more or less the same from year to year, regardless of crop load. Obviously, greater tonnage will mean more cartons of a given size-though the percentage of that size is unchanged. Note, however, that this does not hold true when there is a rather light crop load or young trees which have not achieved full production as yet.

What determines final fruit size? First, the potential size of a piece of fruit is determined by the number of cells that are formed in that fruit. Cell division in the developing fruit occurs up until the end of the fruit drop periods. That usually occurs around May 20, give or take a few days, in Texas. Thus, the more cells that form, the greater the potential size, so the need for water and other cultural inputs during this critical period is essential to maximize cell division.

From late May until harvest, fruit size increases by the enlargement of the cells that are already present. Hot, dry weather, such as occurs in the Valley during the summers, can slow cell (and fruit) enlargement, but the potential size will ultimately be attained, given time and more favorable conditions.

Why are some fruit larger than others? For the most part, the larger grapefruit on a tree develop from flowers that form earlier than the others. Usually, these flowers are situated in a more preferential position on the tree or branch so that they out-compete other fruit.

According to work by Dr. John Fucik many years ago, Valley grapefruit increases about one commercial size each month it remains on the tree during the fall into early winter. In other words, a size 36 in October could be a size 27 in December.

That's why some growers do not like to harvest in October or November, as the fruit is not so large as it will be in December, so they lose tonnage. While it is true that tonnage is lower in an early harvest, this loss is normally offset by the relatively greater increase in size of the remaining fruit.

Indeed, if groves are not ring-picked in the fall, the largest fruit often become so large, and possibly coarse and puffy, that they often are not suitable for the fresh market. Too, the smaller fruit tend to stay small because they simply cannot compete with these larger fruit. In an ideal world, it would be preferable to do two or even three ring pickings through the season.

JULIAN W. SAULS, Ph.D.
Professor & Extension Horticulturist
2401 East Highway 83
Weslaco TX 78596