|SEPTEMBER, 1998 VOL. 12, NO. 9
WATER METERS & CONSERVATION
WATER METERS AND CONSERVATION-
A recent engineering study estimated that metering of agricultural irrigation could save nearly a quarter of a million acre-feet of water annually-at an initial cost of about $7 million. The cost comes out to about $12 per acre on average-but considering, say, $700 as the cost of a meter, each meter would have to service about 60 acres to make that average. Granted, portable meters can handle a lot of acres of row crops, as they can be moved from field to field. However, a meter for a 20-acre citrus grove under permanent value irrigation would most commonly be built into the system-thereby costing as much as $35 per acre.
Nonetheless, water metering does not, in and of itself, save any water-metering only records the amount of water used. So, how can someone even suggest that metering would save that much water (which figures out to about 16.5 percent of total authorized water rights)?
The premise is that metering would limit the amount of water used on a particular parcel of agricultural cropland to only that amount which is allocated to it-both in years of plenty as well as in years of short supply. When the allocation is gone, it's over-unless additional water is transferred from other cropland or from outside. Thus, all irrigated land would be assured of receiving its equitable share of the allocated water.
It is my firm conviction that citrus growers in particular would benefit from totally metered water. Since most districts usually start running out of water when all of the spring and summer row crops have been completed, the present situation leaves many citrus growers with a positive water balance that the district cannot deliver-and orchards that start to decline for lack of water.
Based upon results in the last two seasons, metered water to citrus groves is running between 4.0 and 5.0 acre inches per full irrigation, thereby proving that citrus uses considerably less water than the district average. In other words, citrus groves have actually been subsidizing the water used in other agricultural production-but get cut off when the district runs out.
As you know, there have been substantial inflows into both reservoirs, with early estimates being over 300,000 acres feet of new water. The new irrigation allocations that are forthcoming are indeed welcome, especially by citrus groves and cane fields that have been too long with too little or no water this summer. Still, the relief comes at a high price in the terms of the losses of life and property that occurred from the heavy rains and resultant flooding upriver.
How much water was gained and how much will be available for allocation are yet to be determined. It would behoove all irrigators to use this new water judiciously, as the reservoirs are still critically low and we must continue to practice conservation irrigation rather than business as usual.
The public perception that agriculture uses nearly 90 percent of the water (of the total conservation level), is one that we in agriculture must not ignore. It doesn't matter to the general public that agriculture "owns" that much water, nor that agricultural water use does not take water away from municipalities. The fact is that agriculture is perceived by the general public to be both a high user and a waster of water, so we must be conscious of that perception and practice conservation is agriculture.
IRRIGATING STRESSED ORCHARDS-
In citrus groves that have not had water since June or early July, the soil reservoir is nearly, if not totally, depleted. It cannot easily be replenished in a single irrigation. In flood irrigated orchards, the natural tendency is to irrigate quickly so that the entire orchard can receive water without further delay. Assuming that normal September rains occur, it makes sense to run the water fast-and leave total replenishment of the soil profile to (hoped for) rains and/or subsequent irrigation. To irrigate faster than normal, irrigate fewer pans (or rows) so as to push water quickly down row and move on across the orchard.
For microsprayer groves having gone too long without water, do not try to make up for lost time by irrigating for a long time. To do so excludes air from the wetted root zone, which is detrimental to root uptake of both water and nutrients from the soil. The better course is to provide a normal irrigation now, then shorten the normal interval to the next irrigation. Again, the idea is to provide water quickly to start the trees toward recovery and worry about replenishment of the soil profile later.
CITRUS PEST UPDATE-
Rust mite populations have been observed in a few groves and have been increasing due to some isolated showers in August. Although these populations are at nontreatable levels, continued close monitoring will be required since much damage can result from these fall populations. The armored scale complex, especially Florida red scale, has also been increasing to treatable levels this summer. Chemical control using Lorsban or Supracide has proven ineffective in the past for Florida red scale but are still effective against California red scale and chaff scale. These scale populations are quite varied and should be closely monitored since they can cause serious downgrading of fruit. False spider mite damage on grapefruit has been reported from many groves, especially in western Hidalgo county. False spider mites can cause serious damage on grapefruit and should be quickly treated; little to no damage generally occurs on oranges. Several species of false spider mite exist and may account for differences where false spider mites are easily found but no damage (leprosis) can be found. On the same note, false spider mite populations can increase if organophospate insecticides are being used to control armored scale populations.
Texas citrus mites, mealybugs, and whitefly are all rapidly increasing but these populations are quite varied; some groves may require action for these pests. Citrus leafminer populations have been increasing in some areas (Cameron County) on the new growth but still remain at low levels in these orchards. Citrus blackfly populations continue to increase but are still at low levels. Also, more twig dieback is being reported across the Valley. Twig dieback can be caused by fungi, although non-pathogenic factors such as water stress may be the cause of this year's problem; investigations are on-going.
CITRUS WEB SITE-
We are in the process of developing a Texas citrus website, to be located in the aggie-horticulture web at College Station. I have contracted with one of the major developers of the aggie-horticulture site to develop ours. The control for the citrus site will be in my office, but access will be through the server that Dr. Dan Lineberger maintains for aggie-horticulture.
The basic format will be similar to the Texas Citrus Handbook, with some important additions. One section will list, describe and refer to the various organizations in the Texas citrus industry. Another section is intended to list all of the commercial shippers, while another will endeavor to list all of the gift fruit shippers.
Too, we intend to include a section on current prices, with links to sources of f.o.b. price data. Naturally, we want to provide links to any organization, shipper, gift fruit shipper, et cetera that has web sites.
Presently, Dr. Vic French is heading the effort to update the photographs of the various insect and mite pests and Dr. Mani Skaria is doing the same for diseases. For the most part, they will utilize transparencies that they already have to be transformed to digital format for inclusion in the website.
Obviously, this is no small undertaking-and will require lots of work and telephone calls from me and Dr. Jason Johnson, Extension Economist, to get all of the pertinent data on packinghouses, gift fruit shippers, organizations, potential linkages, et cetera.
Our timeline is to be on-line by the end of the year. Our success in making that deadline will depend upon the cooperation of our organizations and shippers-both commercial and gift fruit.
TEXAS PRODUCE CONVENTION-
The annual Texas Produce Convention is rapidly approaching -September 9-12 at the South Padre Island Convention Center. If you haven't already registered, you'll have to do so at the door and take your chances on the availability of tickets for some of the associated meals and functions. Contact Texas Produce Association, Texas Vegetable Association or Texas Citrus Mutual if you need last-minute information.
Rainfall has been hit or miss, mostly the latter-even the hits haven't amounted to much in terms of significant improvement in soil moisture levels.
Pest control has not been a major problem because of lack of rain. The situation could change rapidly as shower activity increases and temperatures cool in September. Check Juan Anciso's article for more information.
There is Tree Assistance Program (TAP) funding available for citrus growers who have lost trees or suffered extensive drought damage. Application deadline is September 15. Basically, it looks like the program will pay a flat rate for eligible practices such as dead tree removal and replacement or pruning of drought-killed limbs. The program has a 20 percent deductible and a $25,000 maximum per grower.
Navel oranges are really splitting lately and I have seen more round oranges splitting than I can recall. The situation was not unexpected, given the hot, dry summer and limited irrigation.
Harvest will start up this month as the first oranges pass maturity standards. Activity will be limited until Marrs and navels meet standards, after which grapefruit will pass and it's off to the races on the new season.
JULIAN W. SAULS, Ph.D.
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