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FALL WEED CONTROL
FALL WEED CONTROL-
Weed growth has really flourished since the rains commenced back at the first of September-especially where late summer herbicides were not put on. Continued rains over the last three months have hampered weed control-whether mechanical or chemical.
Many growers are reluctant to apply herbicides, even contact materials, so late in the season-partly because of harvesting and partly because of knocking too much fruit off with the booms. In the first regard, Roundup® has a one-day pre-harvest interval, so its use should not really affect harvesting. Touchdown® has a 13-day interval between application and harvest.
As for the booms knocking off a lot of fruit, that does happen for sure-more so in grapefruit than oranges since grapefruit are more easily separated from the stem than oranges, the fruit are larger and the growth habit of grapefruit trees is such that a lot of fruit hangs near the ground.
Because fall is an excellent time to knock out tough weeds like guinea grass, chemical companies, growers and caretakers in Florida developed some novel designs for herbicide booms to reduce drift, improve coverage and greatly reduce the amount of fruit knocked off. For the most part, these booms are overlage in both height and width. Such oversizing provides a large, round leading edge and tip which allows most low-hanging fruit and limbs to slide up and over the boom, while also pressing down grass and weeds for better coverage and completely containing the spray inside the boom.
Most of the booms incorporate hydraulic cylinders for leveling during operation and for raising for transport. Many include air shocks for breakaway and small-diameter, wide wheels or skids near the tip to preclude the boom getting too low. Air shocks slowly return the boom to its normal position after breakaway, thus providing better coverage as it returns and less fruit damage than occurs with most spring breakaways. Some designs utilize a rear guard or shield made from heavy canvas conveyor belting-the canvas belting is far more durable than carpeting and it soon becomes wet during operation, thereby providing a wicking action for contact herbicides.
To further reduce fruit damage, ground speed must be reduced. Since both Roundup® and Touchdown® are used as a percentage of the spray volume, slower ground speeds require smaller diameter spray tips to reduce total gallons of spray per acre to a level that utilizes about the same amount of actual herbicide per acre.
For the most part, these booms use teejets rather than floodjets, with 110 nozzles rather than 80 -spaced 10 to 12 inches apart, depending upon mounting height inside the boom. The boom tips often incorporate a pair of offset nozzles of the same orifice size to extend coverage beyond the boom tip.
The large booms offer another advantage that should be useful in Texas orchards wherein grassy weeds are usually more problematic near the low end of the orchard, i.e., the ability to incorporate a second herbicide line in the boom. The extra line can then be turned on as needed to increase the amount of herbicide applied to problem areas without having to reduce speed or increase pressure.
VALLEY CITRUS DAY-
The annual Valley Citrus Day is scheduled for December 15th in the auditorium at Rio Farms in Monte Alto. The program starts with registration at 8:00 am and concludes with lunch. In the first session starting at 8:30, Dr. Jesusa Legaspi will talk about biocontrol of Florida red scale, Dr. Vic French will discuss ants and pest management, followed by Dr. Juan Anciso on citrus IPM.
After the break, I'll talk about well waters, Floyd Engeling will discuss the experience of Rio Grande Nursery with electrostatic precipitators to neutralize salts and Richard Hagan will close it out with a discussion of weather patterns, particularly with respect to rainfall and drought.
There is no charge for the program and lunch will be provided. The morning session will provide 1.5 CEU's for pesticide licensing. After lunch, an additional 1.5 CEU's in drift management will be offered for those who care to stay for it. As you know, drift control is a required topic that is sometimes difficult to obtain-so here's your chance.
As you know, the Texas citrus website (http://aggie-horticulture.tamu.edu/citrus/) has been online for about six weeks. I had hoped to have additional information posted by now, such as writeups about the various industry organizations, shippers, personnel et cetera. Unfortunately, the stuff that is ready is insufficient to hire outside help and I'm still learning how to post it myself-so I'm waiting for the other information or until I have more confidence in my ability to post it-whichever comes first. It is looking like the latter will win out.
Meanwhile, you might be interested to know that 13 of the 38 gift-fruit shippers have websites-to which we will link when the list of gift-fruit shippers gets posted. Some 18 have E-mail addresses. Among the 16 commercial shippers, eight have or are included in websites, to which we will link, and 10 have E-mail. Between the two, there are a actually 17 websites (since four of the commercial shippers with websites also have gift fruit operations).
As for the Texas citrus website, it was visited 2,913 times during November, involving nearly 40,000 kb of information transferred in 700 sessions. Those numbers may seem high-and they are when you consider that that many people, most of whom we don't know, were looking for information about Texas citrus. I should point out, however, that the entire Aggie-Horticulture website where ours is located logged 642,879 hits and 286,725 pages transferred in 152,118 sessions during November.
The rains have let up sufficiently in enough orchards that harvesting operations have kept fruit moving to market, but wet soils from periodic rains continue to plague some orchards. Overall fruit movement has caught up with last season in both grapefruit and navels, although early oranges are still lagging as of November 21.
Quality is excellent from what I have seen. While I expected size to be down somewhat from too little water, the orchards I have seen seem to have plenty of large fruit. Too, Rio fruit that I have seen appears to have some of the best shape ever-with very little sheepnosing apparent.
Both pest problems and weed problems reflect the weather of the last three months and the inability to enter water-soaked orchards to provide timely controls.
All subscriptions to Valley Citrus Notes expire with this issue, although you will receive both the January and February issues even if you don't renew. The subscription fee is $12.00 per year, payable to Texas Agricultural Extension Service, Acct. No. 237207.
The usual scenario is that folks just keep forgetting to renew, then got cut in March, don't miss it for a couple of months, then wonder why they don't get it anymore. Sound familiar?
CITRUS PEST UPDATE-
With the harvest of citrus underway, many of the problems that were not realized during the growing season become more obvious with the results of the harvest. One problem that has surfaced has been scale causing the downgrading of fruit. The primary problem has been with the armored scales such California red, Florida red, and chaff scale. Their feeding results in spotting fruit wherein the feeding sites do not color from green to yellow or orange at maturity, thus, failing fruit marketing standards.
Oil sprays are least injurious of all scalicides to scale parasitoid populations but oil can not be used after September 15 because it deters soluble solids (which affects maturity standards for grapefruit) and delays coloring of all types of fruit. Therefore, if spherical yellow crawlers (immature stage) are still encountered, repeated applications of Lorsban® or Supracide® will be required just to lessen any scale problem for the time being.
Also, melanose on the fruit has been extremely heavy in some groves and possibly attributed to the extremely wet fall as well. Fruit samples of these diseases as well as mite damage will be available for identification purposes at the Valley Citrus Conference on December 15,1998, at Rio Farms which will address these pest problems and water issues that were encountered this year.
JULIAN W. SAULS, Ph.D.
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