GRAPEFRUIT JUICE-MEDICATION INTERACTIONS
WATER
HEDGING AND TOPPING
FRUIT SET
FRUIT MOVEMENT

GRAPEFRUIT JUICE-MEDICATION INTERACTIONS-

We have all heard about the grapefruit juice and prescription drug interactions, but most of us have no idea where to look for information about a specific medication. Fortunately, concern by the consuming public, the producers of grapefruit and the medical profession has focused a lot of attention and research on the matter.

Pharmacology experts with the University of Florida and Tufts University established a Center for Food-Drug Interaction Research and Education in 2003, with funding primarily from USDA and the Florida Department of Citrus. The Center's mission is basically to bring together research workers in pharmacology, medicine and food science to identify and analyze potential interactions and their effects. Naturally, the Center is focusing on grapefruit juice initially.

The Center has established a website to assist in the education component of its work: http://www.druginteractioncenter.org. The site is broken down into two components-one for consumers and one for professionals. In the consumer section, various medications are broken down by Category, by Compound Name and by Brand Name. Within each of these groups, the interaction of grapefruit juice is shown for each product, with a red, yellow, green rating beside the category, compound or brand name.

Red indicates a strong interaction with grapefruit juice, yellow indicates a moderate interaction, while green means a weak interaction, i.e., one that is unlikely to be clinically significant. So, anyone who likes grapefruit can quickly check for the level of interaction that might exist for whatever medication that person is using.

But, that's not all-there are listings of alternative, non-interacting drugs within the same class that may be effective also. There are detailed research summaries for professionals and simplified summaries for consumers, as well as links to all currently published research studies, as well as pharmacological details of currently documented interactions.

So, if you love your grapefruit but have foregone the pleasure because of concerns for your health, check out the website for your respective medication. And, pass the word along to your doctor or doctors as well as your pharmacists about this great website. Who knows, in consultations with your medical professionals and using the information in this website, you may find that you can have your grapefruit again.

WATER-

You don't have to drive to the reservoirs to learn that there is apparently plenty of water behind the dams; just drive along some of the secondary or rural roads almost anywhere in the Valley and you'll figure it out pretty quickly. The answer is in the tremendous amount of irrigation tailwater and/or overirrigation running out of rural yards and fields of cotton, corn, grain, cane, pastures, et cetera (so far, I haven't seen any water running out of citrus groves, and I have looked). And it appears to me that there are more ditches and less poly pipe or gated pipe in use. With all the waste that is occurring, one would think that water is not now nor has ever been in short supply for irrigation-how soon we forget.

For the record, yes, the current US share of water in the two reservoirs is at 102.5 percent of conservation level, though Mexico's share is down to 38.3 percent of conservation level. Don't forget that if Mexico is unable to deliver on its promise to retire another chunk of its debt by inflows of new water, they will make another in-storage transfer of ownership, i.e., part of that 38.3 percent.

In addition, there has been some talk that the drought is ended; though I am not sure about that. In checking my own rainfall records, there has been no significant rainfall since the first of October; quite a few recordings of "trace" and less than a quarter inch, but nothing substantial. The Christmas snow was about the most precipitation my groves have seen during the last seven months, but if memory serves, snowfall measures 10 to 12 times as much as rainfall, which is to say that three inches of snow is equivalent to only a quarter inch of rain, and I don't think my groves had anywhere near three inches of snow.

Well, Cinco de Mayo is this week, and there is a pretty good history of significant thundershowers around that date and the local forecasters are showing "chances" for rain with the next unseasonal cool front that is due for arrival about mid-week. Despite history and current forecasts, I plan to continue the existing irrigation schedule until the rain comes.

HEDGING AND TOPPING-

The pruning equipment has really been busy the last couple of months as harvesting crews finish with grapefruit groves. It appears to me that a lot of growers are opting for lower tops, based on what I have observed in recently pruned orchards, many are being topped well below 12 feet, some as low as nine. It could be that some growers figure that they don't have much fruit anyway, so heavier cutting wouldn't affect production in the current season anyway.

Lower tops are probably not a bad idea, as that opens up the interior of the tree to sunlight, thereby resulting in the development of more interior fruiting twigs than would otherwise be the case. Rio Red is such a vigorous tree that it suffers tremendous interior wood dieoff from shading, not just the usual small, fruiting twigs, but substantially larger branches up to an inch or so in diameter.

FRUIT SET-

I still don't know what to make of this year's flowering and fruit set situation in grapefruit. The more growers I talk with, the more I hear the same story; a precious few fruit that are about the size of a golf ball, a few more in almost every size down to just recently bloomed. Too, there are apparently a lot of trees that have virtually no fruit of any size, as they just didn't bloom.

My best guess is that significant defoliation of intact, green leaves following the snow resulted in an early growth flush which had not yet had flower buds induced. If that flush was pretty strong, there would have been only a very limited flush near the normal time, which naturally would have had only limited flowering.

I would not be at all surprised to see some additional flowering on those trees in the next growth flush. Obviously, any flowering at this point would probably not be desirable, as it would result in so-called "June bloom" fruit. In case you've forgotten, June bloom fruit is usually overly large, thick skinned, coarse, and has poor internal quality. Too, in grapefruit, especially Rio, severe sheepnosing would be likely.

FRUIT MOVEMENT-

On April 8, the folks involved in estimating the citrus crop raised the estimate for Texas grapefruit by almost 5 percent and Texas early/mid oranges by about 14 percent, while lowering the Valencia estimate by 8 percent. While there should be no real problem with extending grapefruit, the same cannot be said for early/mid oranges. The latter should be substantially overmature and undergoing heavy droppage rates by now and woodpeckers are really hitting them hard everywhere I look.

Export grapefruit will scare a million cartons this season, up substantially from prior seasons. However, despite the increased exports and the increased total supply, the overall utilization of fresh citrus will be hard pressed to reach the final volume achieved last season (about 8.8 million cartons), as movement is currently about 90 percent of the volume shipped at the same time last season.

Orange volume to processing is reflective of too much fruit, insect/mite damage and the natural "beauty marks" of excessive windscarring of the fruit. Fully 30 percent of Texas oranges have gone to processing this season, with a lot of fruit apparently still out there. Last year's final for all oranges was about 34 percent to processing.

Grapefruit's external quality problems are worse, as fruit size and shape are additional major grade-lowering factors in grapefruit. Last year's final volume processed was about 42 percent; it is currently running about 52 percent. Another thing about grapefruit-when the demand for Texas Choice grapefruit is lower than its supply (which is almost always the case), a lot of those No. 2's necessarily end up in processing, as packinghouses can only hold them so long while they attempt to sell them.

If you turn the numbers around, about 66 percent of Texas oranges were utilized fresh in the 2003-04 season, while about 58 percent of Texas grapefruit went fresh.

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