VALLEY CITRUS NOTES RENEWAL
UTILIZATION REPORTS
CITRUS MOVEMENT
VALLEY WATER
NUTRITION
ALTERNATE BEARING AND FRUIT SHAPE
SHORTS

VALLEY CITRUS NOTES RENEWAL-

Judging from responses to date, most of you would rather pay the $12.00 to get a 'snail-mail' hard copy of Valley Citrus Notes, as there have not been as many e-mail addresses sent in as I would have expected. No matter-I write it anyway, so it's your choice as to if and how you receive it.

Final reminder-renew for $12.00 or send your e-mail address to (l-cardenas@tamu.edu) in order to get the March and subsequent issues.

UTILIZATION REPORTS-

I have been working with TVCC to get the Weekly Utilization Reports via e-mail so that I can post them regularly on the website. We have worked out the bugs to get the reports to me-but now I'm working on a couple of bugs in my system to convert the Excel spreadsheet files into web documents that other computers can access. Hopefully, we will have these on-line within a couple of weeks. Look for them at http://aggie-horticulture.tamu.edu/citrus/ reports.

CITRUS MOVEMENT-

In looking at the numbers in Texas Valley Citrus Committee's Fresh Fruit Utilization Report for January 22, I find some interesting numbers. For example, total fresh shipments of Texas citrus are up nearly 15 percent over last season at this time. Grapefruit movement is up 17.0 percent, navel volume is up 19.8 percent, while early orange shipments are barely up 2.0 percent.

The navel crop has been a little bit of a surprise. Although it is nearly finished, fresh shipments have already surpassed last season's final total volume by some 15.4 percent, i.e., about 70,500 additional cartons.

Because relative packouts don't vary a whole lot from year to year, the percentage of eliminations can be an indicator of overall general quality of the crop with regard to external appearance. This season was expected to have more sheepnosing than last, and rust mite control was somewhat problematic in some groves. Too, melanose really picked up in some orchards this season as a consequence of drought damage in the summer of 1998. Sure enough, grapefruit eliminations to date represent almost 24 percent of the harvest, as compared to barely 19 percent at this time last year.

VALLEY WATER-

The Valley Irrigation Conference is scheduled at the Mercedes Livestock Show grounds on Thursday, February 3. I did not receive sufficient notice and information to publicize it last month-and many won't get this until the day of the conference. The program has some good topics, although much of it is directed at row crops rather than orchard crops.

Still, supplies going into this season are not more than about 1.0 percent above where we started last season. In other words, there isn't enough irrigation water behind the dams to carry the upcoming citrus crop to maturity-unless we get plentiful and timely rainfall to attenuate the demand for water in both row crops and in orchards.

So, use it wisely while we have it; maybe it will stretch a little further if everyone does their part to conserve without stressing the crops.

NUTRITION-

Growers who haven't already fertilized will be doing so in advance of the next irrigation. In general, mature orchards should be getting about 150 units of nitrogen per acre. Two notable exceptions could be Rio orchards and microsprayer blocks. In the case of Rio, refer to the following article. As for microsprayer fertigation, the efficiency of microsprayers suggests that 15 to 20 percent less nitrogen should be applied.

I still like split applications, despite the added cost of application. The split allows adjustments in the total fertilizer program after fruit set has been accomplished. For example, a heavy set may require a little more nitrogen than normal; a light set may require a little less. Thus, saving about a third of the total nitrogen until fruit set can be evaluated makes sense-especially when your Rio block received a full fertilization pre-bloom, but had a relatively low set in 1999.

Although microsprayer fertigation is a great way to fertilize, one problem I have noted is that the fertilizer injection schedule can sometimes be disrupted by a spell of rainy weather. In other words, you must irrigate to fertilize, yet it is sometimes too wet to irrigate. Some growers have solved that problem by applying about a third of the total nitrogen, from dry material, at the start of the season. Using a directional attachment, the spreader is run in alternate middles only.

ALTERNATE BEARING AND FRUIT SHAPE-

From the records of the total grapefruit production, as well as those of several growers, it is obvious that Rio Red is showing a strong tendency to alternate bearing, i.e., a heavy crop followed by a reduced crop followed by a heavy crop again. The 1998-99 Rio crop was rather large, but production in many orchards is down in the current season. The coming bloom should set a heavy crop again.

With a normal fertilizer program year in and year out, without regard to total set, what happens is that the trees don't make as much growth during the heavy crop year, since the available nutrition is directed toward the heavy crop. Thus, the reduced growth results in a lighter bloom and set in the next season. Then, the normal fertilization program is too much for the light crop, so the trees make excess growth, setting up a heavy bloom and set in the following year-and the light crop is coarser, larger and exhibits more severe sheepnosing.

As time progresses, the swing between heavy and light crop years can get wider and wider. About the only way to attenuate the problem is to fertilize less in light crop years and more in heavy crop years, thereby trying to keep growth (and production) closer to normal. This is the major reason that I like split applications for Rio Red orchards. With about 2/3 of the nitrogen applied pre-bloom, the grower can then adjust the total based on crop set, i.e., reduce the split to 25 or 30 pounds for a light crop or boost it to 75 or 80 pounds for a heavy crop.

Another factor that growers should consider is that nutrition per se does not cause sheepnosing-but it does affect the severity of the sheepnosing that occurs. In other words, if sheepnosing is present (and when isn't it in Rio), excess nitrogen will worsen the degree of sheepnosing, changing slight sheepnosing to moderate and moderate to severe. Go look at the fruit in a light-crop Rio orchard and compare that to fruit in a heavy-crop orchard.

So, what it adds up to is that Rio Red fruit shape in a light-crop season could be helped a little if there were less total nitrogen available to the trees. That is not to say that I would routinely put a single application of 120-125 pounds of nitrogen pre-bloom to a Rio Red orchard that just bore a heavy crop nor would I would apply 175-180 pounds to one which just harvested a light crop. To be sure, I prefer the split application so as to more accurately manage orchard nutrition and hopefully attenuate both alternate bearing and the severity of existing sheepnosing.

For the record, Marrs orchards are also in an alternate bearing mode, as are Pineapple oranges (i.e., the true Pineapple that doesn't mature until about Thanksgiving, not the Parson Brown that some call Pineapple). Adjustments to nitrogen levels should also be practiced in those groves in response to fruit set.

SHORTS-

I know you are aware that citrus canker has moved into South Dade County's lime production area, just as it has continued to elude eradication efforts in other areas of Florida. The situation is becoming increasingly dire, overshadowing the combined threat of brown citrus aphid and tristeza.

Locally, there are some reports of budbreak in orchards. Obviously, the mild temperatures in January contributed to this activity. What I have noted, however, is not a general budbreak as one would expect for the spring flush. Rather, the feathery new growth and white flower buds are limited to terminals that were defoliated overwinter because of low humidity and Texas citrus mite damage. I have yet to see any activity on non-defoliated terminals, even in navels, which are the earliest to flush.

Have you heard that the price of processed grapefruit is at $80 per ton delivered in? Even after pick-and-haul, plus packinghouse elimination charges and TCX reserves, you should be looking at about $40 per ton net to the grower. While that price should serve as a floor for Choice grade, you have to average at least $0.80 per carton above pick-pack-and-sell charges on your Choice grade fruit in order to equal that juice price.

Growers are getting ready to fertilize, herbicide and irrigate in preparation for the coming bloom. If you are planning to use Temik®, the earlier you can get it out and watered in, the better. There is simply no benefit of waiting beyond mid-April to apply Temik®. On the other hand, if your grapefruit had melanose damage this season, you would be better served with spraying, as you will need a fungicide in post-bloom and in late spring to suppress the melanose problem.

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