TEXAS PRODUCE CONVENTION
CITRUS GREENING DISEASE IN BRAZIL
WATER LEVELS
C-PROBE UPDATE
VALUE-ADDED
CURRENTLY

TEXAS PRODUCE CONVENTION-

This annual event is co-hosted by Texas Citrus Mutual, Texas Vegetable Association and Texas Produce Association. In a popular move, this year's event is returning to San Antonio. The dates are August 12-14, 2004; the headquarters is the Westin-Riverwalk Hotel downtown.

The Trade Show format has been changed to a "table top exhibits" Mini-Expo, scheduled for Thursday evening along with the opening reception. The customary golf tournament is scheduled for the Golf Club of Texas at Briggs Ranch southwest of town, starting at 11:00 on Thursday.

Excepting for the various board meetings, the rest of the program is scheduled for Friday, including breakfast, general sessions, lunch, commodity sessions, ending with Casino Night and Silent Auction. For citrus interests, Dr. Victor French will discuss blackfly and rust mite, Dr. John Robinson will discuss value-added citrus opportunities, Dr. John da Graca will discuss alternatives to sour orange, and Dr. Bhimu Patil will talk about grapefruit. An update on mexfly regulations had not been confirmed at this time.

CITRUS GREENING DISEASE IN BRAZIL-

The mysterious disease that has been attacking orange trees in Brazil has been identified by officials as the most dangerous strain of Asian citrus greening. According to the announcement, greening is both insect vectored and graft transmissible. Control is suggested by destruction of affected groves and local insect control.

WATER LEVELS-

Reservoir levels have remained high through the summer, as timely rainfall has resulted in additional inflows and also reduced irrigation demand. In addition, the summer usually sees a slacking of irrigation demand as the winter-spring crops are gone and the harvest of grain (mostly June), corn (June and July) and cotton (July and August) commences leaving mostly citrus and cane with irrigation needs. The next major irrigation demand will come as growers prepare for the planting of vegetables and perhaps some fall corn.

C-PROBE UPDATE-

These instruments continue to amaze me. A colleague in Florida sent me some interesting comments regarding my analysis of the times of soil moisture depletion in relation to the physiological process of photosynthesis. His comments were basically that the amount of water used in photosynthesis is relatively minor, especially in comparison to that which evaporates through the stomata when they open during the day to permit the absorption of carbon dioxide from the air. And he's right, of course.

In addition, another month of analyses of the C-Probe data does not show the same patterns of soil moisture depletion that were apparent at the time I wrote last month's analysis. In essence, it appears that the probes were not completely sealed until the occurrence of about 6 inches of rain during the last week of June, so the readings were not exactly reliable (I should know better than to speculate before I was totally sure that the readings were valid!).

Hidalgo Soil. In the Hidalgo sandy clay loam soil, soil moisture was depleted most from early afternoon until night, with steady, lesser depletion continuously until about mid-morning. A couple of hours of replenishment occurred until about noon, and then the same pattern repeats. In this soil, the curves for the 8-inch depth were shifted about an hour earlier, while the curves for the 12-inch depth were slightly earlier still.

Interestingly, at the 20-inch depth, there are only very minor fluctuations in the depletion rate for about a week following irrigation, and then dramatic depletion occurs. This is either 1) the upward movement of water to replenish that which is being rapidly depleted at the 4-, 8-, and 12-inch depths, 2) increased root activity at the lower depth to compensate for the inability of roots in the top foot of soil to obtain enough water, or 3) a combination of the two. I lean towards the latter option, as there are roots at or very near the 20-inch depth and soil moisture does move upwards in soils through capillary action.

Depletion at the 36-inch depth was very minor. Soil moisture levels at that depth increase rapidly during the course of an irrigation or following significant rainfall, but drop back to approximately the same levels as before the irrigation or rainfall within about 3 days. Obviously, it takes about 3 days in this soil for excess water at upper depths to percolate beyond 3 feet.

Racombes Soil. Soil moisture depletion patterns in the Racombes sandy clay loam soil were similar, but with enough differences to be worthy of mention. Primarily, depletion quits about mid-afternoon rather than mid-morning. Too, unlike the Hidalgo soil having a period of steep depletion in the afternoon and early evening, followed by a period of lesser depletion, the Racombes soil depletion was more or less steady from late afternoon through the night until about early to mid-afternoon the next day.

Too, only very minor fluctuations in depletion occurred at the 12-inch depth, but there were daily fluctuations at the 20-inch depth. Readings at the 36-inch depth paralleled those in the Hidalgo soil.

Trees in the Racombes soil are mature Rio Red grapefruit planted 15 X 25 in east-west rows; those in the Hidalgo soil are young bearing Olinda Valencia oranges planted 12.5 X 25 in north-south rows-both on sour. Both are under micro-sprayer irrigation-the grapefruit for about 15 months, the oranges since planting. The different soil moisture depletion curves in the two soils may be due more to the different tree ages and the adaptation of the grapefruit to micro-sprayer irrigation than to differences between the two soils. Time will certainly provide better answers.

VALUE-ADDED

Because the term itself implies that the end-product has a higher value, the extension of that is that growers would receive higher value for their raw product. Given that, it would be hard to argue with the concept.

Citrus is perceived as a "messy" fruit to prepare and eat or drink, which is one reason for the decline in fresh citrus consumption in our eat-on-the-run society. Labor costs to do the preparation are viewed as prohibitive, both by the citrus industry and by the food service industry.

Florida has long been involved in research to develop better means to peel, slice, section or otherwise prepare fresh citrus for use in food service as well as for consumer use. The Florida Department of Citrus did indeed develop what appeared to be a phenomenal means to remove the peel and albedo tissue from citrus-but a recent effort by Del Monte to commercialize it has been abandoned, with some finger pointing both ways.

At the Texas Citrus Growers League Annual Meeting last month, a video presentation of a system that will core, peel and slice grapefruit and oranges (sort of like pineapple slices) was shown. This system is being considered within our industry through grant applications to provide major funding-the units aren't cheap, but they aren't prohibitively expensive either.

It appears that the system will work-but the finished product must still be packaged and marketed, the latter of which requires acceptance by intended buyers, whether food service or retail consumers. It is an idea whose time is long overdue in citrus-and the intense red color of Texas Rio Star grapefruit should make it a very attractive option.

What's in it for growers? It's an alternative (to juice) that may provide higher returns for a portion of the crop that does not go fresh, this includes not only eliminations but also a lot of No. 2 grapefruit that does not sell soon after its run through the packinghouse. Grapefruit juice is a value-added product, too-but returns rarely exceed the costs of harvest and elimination and processing.

CURRENTLY-

The good rains of June have resulted in a very good summer growth flush. Indeed, groves are looking as good as I can recall seeing them in the last 25 years. Isolated rains also occurred in some areas in late July.

Citrus rust mites are still around, as are the usual plethora of citrus pests such as scales, other mites and blackflies-so grower vigilance is still critical to maintaining clean fruit and healthy trees. Conditions are right for greasy spot infections of the new (and older) flushes, so preventative fungicides are essential to maintain leaf retention.

The normal decline of residual herbicidal control was hastened by the heavy rains of June to the point that re-application may be necessary sooner than in the last few years. As you know, a clean orchard floor is easier and less expensive to maintain than it is to obtain.

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