IN THIS ISSUE:

ARGENTINA CITRUS
SUMMER PEST CONTROL
APOLOGIES
IRRIGATION SUPPLY
TCX JUICE POOLS

ARGENTINA CITRUS-

After a couple of years of hearings and several years of negotiations (and a recent meeting between the presidents of both countries), the USDA has ruled that citrus from Argentina could be imported into the U.S. USDA contends that four states in Argentina are free of citrus canker and it claims further that it has a 99% chance of detecting diseases through its import monitoring program.

On the one hand, some Florida growers expect to reciprocally ship grapefruit to Argentina-as Texas has reportedly been doing. I checked the TVCC records-Texas exported only 29,007 total cartons of grapefruit to Argentina during 1995-96, 1996-97 and 1998-99 combined, with none in 1994-95, 1997-98 or 1999-00. That's fewer than 5000 cartons per year over the last six years-not exactly a big deal.

On the other hand, California-Arizona growers are filing suit to have the USDA rule declared invalid because of disease risk from citrus canker, citrus black spot and sweet orange scab, claiming that USDA's estimated odds of detecting those diseases are simply wrong. Naturally, Argentina is claiming protectionism as the basis for the lawsuit.

While Argentina grows oranges and grapefruit, its major product is lemons-of which there are few in Florida and many in California-Arizona. Still, repeated outbreaks of various fruit flies in both Florida and California, plus citrus canker, brown citrus aphid, Asian citrus leafminer and Asian citrus psyllid in Florida are pretty strong evidence of USDA's inability to prevent accidental introductions of foreign citrus pests-despite the differences between an import monitoring program and interception from travelers coming into the U.S. from other countries.

The world is in color-but such matters as this are always grey, with differing perspectives predicated on whose ox is being gored. Don't be surprised if the USDA rule prevails.

SUMMER PEST CONTROL-

After two or three sprays, including one or two behind Temik®, growers whose groves were severely impacted by citrus rust mites finally got some semblance of control-just in time to start thinking about summer spray needs. Spring-applied pest control efforts have either played out or are about to.

The early generation of California red scale has matured and is now producing offspring. While traditional organophosphate scalicides are very good against scale crawlers, they cannot penetrate the mature scale's armor, so scale problems persist. Citrus spray oil controls mature scale by smothering it, thereby breaking the cycle.

Many growers are leery of oil because of potential phytotoxicity under prevailing conditions, of low humidity and high temperatures during the summer. The only phytotoxicity I have observed in Texas citrus from summer oil use has been because of agitation failures, i.e., emulsion of the oil is not maintained, causing almost all of the oil to be sprayed out on the last few trees of a tankload. For added safety with oil, a few wispy clouds in the sky during application helps.

The scale problem and other pests (such as leaf-footed plant bug damage last year) suggest that a combination might be better, as oil controls mature scale while Lorsban® controls crawlers and is effective on leaf-footed plant bug, too. Plant bugs are hard to target, as they migrate in an out of groves at will.

Esteem 0.86® (Valent USA) is a new scalicide that has done well in Dr. Vic French's tests. At 17 ounces/acre, it controls California red scale, black scale and brown soft scale; while about half that rate works on whitefly, blackfly and leafminer. Esteem is an insect growth regulator that is easy on beneficials. It is a little slow to act, so a tank mix with oil is very effective.

Rust mites in problem groves are building again as spring-applied controls begin to break. There are a variety of materials from which to choose, most of which are well-known to growers. Micromite 25WS®(Uniroyal) is another insect growth regulator that has full registration. It is also a little slow to act, but its knockdown is greatly enhanced with oil. The Micromite® (1.25 lb/acre) and oil combination has shown excellent control of leafminer in tests conducted by Dr. Vic French.

Danitol 2.4 EC® (Valent USA) is a newly-labeled insecticide-miticide which has performed well in Dr. Vic French's tests over the last several seasons. At 16 to 21 ounces per acre, it controls blackfly, thrips and the entire mite complex. Both knockdown and residual control were improved when tank mixed with oil.

Leafminer is an ever-present pest, but probably not the primary target of a spray program. Oil residue on the leaf discourages oviposition (egg-laying). Both Agri-Mek and Esteem provide leafminer control; both are enhanced with oil.

Greasy spot is practically ever-present, which is why I suggest including something for greasy spot every time a spray rig goes through the orchard. Oil is fair, as is copper. Benlate®is better but is restricted to mid-June to mid-July application for greasy spot. Enable 2F® (Rohm and Haas) has a section 18 label for Texas grapefruit and is getting rave reviews.

Given the broadest choice of pest control materials that I can remember, including the new ones, choosing the appropriate combination can be difficult. Maybe the choice would be easier if put in the perspective of what you are trying to control (or prevent) with the summer spray.

Citrus rust mite, California red scale and greasy spot are the primary targets. Secondary targets include other mites, other scales, blackfly, whitefly, leafminer and possibly leaf-footed plant bug. Depending upon assessment of the potential importance of those secondary pest targets, the miticide and scalicide combinations that are mutually beneficial and also provide control of important secondary pests is suggested.

APOLOGIES-

No, you weren't left out of the loop this month-I'm just late getting this edition written. The basic problem has been a well-deserved vacation by my secretary, the long weekend and holiday combination and personal commitments this week. My apologies if you have been inconvenienced by the delay.

IRRIGATION SUPPLY-

Current reservoir levels are at 38.75 percent of capacity for the U.S. share-which is up about 2.7 percent from May levels. Considering that cotton, corn and grain are finished (at least water wise) and vegetable pre-watering hasn't started, there isn't much current demand except for citrus, cane and pastures. What is really encouraging is that the current level is down only 2 percent since the start of the year-with the rainy season yet to come. The current situation is more a reflection of ownership transfers from Mexico's supply, plus inflows, than it is to reduced usage or plentiful rainfall.

You might recall that the supply at the start of 1998, 1999 and 2000 was only 40-41 percent of capacity. With any luck, rains in the Trans-Pecos, debt retirement progress from Mexico and timely rains in the Valley could result in the best overall water supply in several years.

TCX JUICE POOLS-

According to the TCX update reported in the June edition of the TCM Grower, 97 percent of the 1998-99 processed grapefruit product has been sold as of the end of May. That's up 5 percent from the end of April, so one might reasonably conclude that that pool will have closed sometime in June-soon to provide needed funds to help pay for those summer sprays growers are currently facing. Now they can start selling the 1999-00 grapefruit juice pool.

The 1999-00 orange juice pool stood at 51 percent sold as of May 31, which was up 8 percent from the April close. At 8 percent per month, it will be about the end of the year before that pool closes.

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


THE INFORMATION GIVEN HEREIN IS FOR EDUCATIONAL PURPOSES ONLY. REFERENCE TO COMMERCIAL PRODUCTS OR TRADE NAMES IS MADE WITH THE UNDERSTANDING THAT NO DISCRIMINATION IS INTENDED AND NO ENDORSEMENT BY THE COOPERATIVE EXTENSION SERVICE IS IMPLIED.


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