IN THIS ISSUE:

CROP MOVEMENT
FRUIT FLY FINDS
WATER SUPPLY
FIRING
FERTILIZATION
OTHER CONSIDERATIONS


CROP MOVEMENT-

Through January 21, shipments of fresh Texas grapefruit were some 36 percent above the volume at the same time last year. Quality, as measured by packinghouse eliminations, is also better, inasmuch as only 30 percent of the harvested tonnage has been eliminated this season in comparison to approximately 40 percent eliminations at this time last year.

Navel orange volume is 23 percent above last season, but earlies are down about 1 percent. In terms of eliminations, orange quality is also well above last season, with only 18 percent of the harvested tonnage being sent to juice in comparison to 30 percent a year ago.

Would that growers could claim all of the credit for the improved packouts, but prevailing weather was a major partner in the effort. Because of weather conditions almost all season, citrus rust mite populations just did not overwhelm our ability to manage them with timely monitoring and spray applications. And anytime rust mites can be readily managed, packouts will be higher.

Prices for Fancy Rio Star are holding in the 10 to 20 dollar range for 56s to 23s, respectively. Early orange prices are holding steady across the board at about $8.00 fob, but Texas navels are no longer being quoted, as they are just about gone.

FRUIT FLY FINDS-

A single immature female sapote fruit fly (Anastrepha serpentina) was trapped in a dooryard lime tree south of Mercedes on January 20, followed by another single fly on January 25 on a sour orange tree about a quarter mile north of the original find. Trapping efforts and fruit cutting in the area have been augmented considerably in order to deal with this problem. As of now, the area is not under quarantine, but that will change if additional flies are discovered in the vicinity.

Two Mexican fruit flies were trapped on January 25, one in a grove north of Mission, the other in a dooryard tree in La Feria. Again, trapping and fruit cutting have increased in the immediate areas.

WATER SUPPLY-

There has been a little decrease in the volume of water stored in Falcon and Amistad Reservoirs, which is due to both evaporation losses and withdrawals for irrigation and urban/industrial use. There has been virtually no significant rainfall either in the watersheds or in the Valley since last fall.

Growers and other water users are encouraged to use their water supplies judiciously, as there is no good reason to waste it. Until normal rains return to the area, we will have to stretch the available water as far as possible.

FIRING-

Entomologists and horticulturists don't always agree on the cause, but area groves (and dooryard trees) have been pretty hard hit by firing in the last couple of months-undoubtedly the worst I have ever seen. Entomologists claim that Texas citrus mite infestations are the culprit and I agree that one can find damaging populations of this pest in some of the affected trees-but I don't see enough of them to account for all the damage that we are seeing this season.

Firing is the term used to describe the shriveling and subsequent droppage of the leaves on the last growth flush-it is also known as mesophyll collapse. During the process, the leaves turn gray, roll up and die. Since that flush is on the perimeter of the trees, the only thing left is bare shoots sticking out from the rest of the tree. Usually, the leaf blades fall leaving the petiole and petiole wings attached-though the latter will ultimately drop as well.

Groves that had been recently harvested and those which are a little short on soil moisture are more severely affected than those which have not been picked or those which were irrigated in the last 4-6 weeks. Physiologically, the fall flush of growth has not hardened off as it should at full maturity. Consequently, such leaves are at greater risk in a moisture stress situation. Add a series of cold fronts that involved air masses of comparatively low relative humidity and you have the necessary conditions for firing.

What does harvesting have to do with it? So long as the fruit is on the tree, the tree will take moisture from the fruit for its own use, but once the fruit is picked, the tree has to rely on what the roots can extract from the soil. Even with good soil moisture, however, firing can and does still occur-which may be where the Texas citrus mites come into the picture.

When you see it, it is already too late to do anything in terms of saving those leaves-but it should be a wakeup call that irrigation is needed.

FERTILIZATION-

If you haven't already, it is time to start the fertilizer buggies rolling, as the spring flush is not that far away. Oranges will likely start to flush in the next two or three weeks, if the present weather patterns hold, but grapefruit usually waits until early to mid March. Either way, it would be good to have the fertilizer on the ground and watered in before the flush kicks off.

In general, the rates for mature trees are about 150 pounds of nitrogen per acre. Because of sheepnosing, I strongly favor splitting the application into 100 pounds now and the balance in May for Rios. Nitrogen does not cause sheepnosing, but it can make it worse. By splitting the application, you have the opportunity to assess fruit set and then decide whether or not you need the second application. Obviously, if set is low, the second application should be scratched, as the first 100 pounds will be more than enough to mature a light crop and provide for the tree as well. If set is normal, make the second application. If set is unusually high, boost the amount in the second application to 75 pounds.

For oranges, a single application is fine. If a strong trend to alternate bearing is in effect, the guide is to reduce the fertilizer to about two-thirds (100 pounds nitrogen per acre) in the "off" or low crop year and to increase it to about 175-180 pounds in the "on" or high crop year. How do you know? With the exception of Valencias and a few oranges that haven't been completed yet, you should know how much the grove picked this year. If harvest was on the low side compared to the prior year, it would be reasonable to expect a higher set this year, so fertilize accordingly.

For Valencias, you just have to make your best estimate of crop load in comparison with what you picked last season and act accordingly. The alternative is to go the split route with 100 pounds now and wait until after harvest when you will know how much the trees produced last year.

OTHER CONSIDERATIONS-

All things considered, there won't be too many groves that won't need irrigation in February. In advance of irrigation, it would be awfully nice to have the fertilizer on the ground and it would be equally nice to have the spring herbicide applications in place so the irrigation can move them both into the soil where they are needed.

In addition, I hark back to the days when Dr. Leon Smith, Dr. Pete Timmer and Dr. Vic French were all working with Temik in Texas citrus. One of the comments that Leon made was that the earlier you could apply Temik, the better. Over the years, that statement has proven to make a whole lot of sense-especially in view of some of the problems that growers have experienced with later-than-normal applications of Temik.

Leon's logic, for which he had solid research support in his tests in area groves, was that early application took down existing overwintering rust mites, which helped it maintain excellent control throughout the spring months and into early summer. Remember when the duration of control from Temik was 120 days or more? Why isn't it that long today?

The product hasn't changed and I know of no evidence that rust mites have become resistant to it. I suspect that our tendency to push the application of Temik further and further into the spring is the reason, as by late March or April, rust mite populations are usually greater and more widespread-both in the tree and in the grove-than they are in late February and early March.

So, methinks it would also be nice to have the Temik rig on hand to apply it just before that coming irrigation.

Just think of it; fertilize, apply herbicide, apply Temik, and then irrigate-all in February. Then, if we should happen to catch some timely rains in the spring, you won't have much to do until summer. Obviously, those growers and caretakers with a lot of acres to manage can't get it all done in February, the rest of us will think about you while we are spending our spring days fishing, golfing or partaking in whatever other diversions we never have enough time to enjoy.


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


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