Valley Citrus Notes

The extensive spraying for dormant season psyllid control has had the not entirely unexpected side effect of causing an upsurge in populations of what has always been considered to be minor pests. The most notable of these is barnacle scale. This pest has been a problem in some groves over the last several years, and experts insist that the problem was self-induced by an overreliance on pesticides that severely reduce the populations of beneficial insects in the grove.

After two consecutive ACP sprays in November and February, barnacle scale has moved into groves where it did not previously exist. Barnacle scale is a wax scale (a “soft” scale) rather than an armored scale, but its body pretty much behaves like an armored scale because of its wax secretions. It is likely that the wax impedes control efforts with standard scale pesticides, as most scalicides control the crawler stage of such scales, but cannot penetrate the wax to control later-stage nymphs and adults.

I questioned Drs. Michael Rogers and Phil Stansly in Florida about controls for barnacle scale. The response was that additional hard insecticides should be avoided in favor of Movento, Knack or citrus spray oil. I failed to ask whether the first two would affect existing adults, but I suspect that the answer would be “not very well” because of the wax. This is not the normal time of year to use citrus spray oil, but five gallons per acre would go a long way towards control of existing adults and nymphs without further disrupting the potential recovery of beneficial insects.

In the long run, the industry needs labeling of some of the better psyllid materials for aerial, low volume and ultra low volume applications, as we cannot continue to wipe out beneficial insects in trying to suppress psyllids.

Barnacle scale is not an exclusive pest of citrus—there are a number of plants that it infests, including wax leaf ligustrum, various Ficus species, gardenia, hawthorn, holly, ornamental pear, quince, morning glory and pyracantha.

As you already know, bloom was quite late this year—navels didn’t start until March, oranges started soon after, and grapefruit bloom was delayed towards the end of the month. Blame the roughly two-week delay on the February freeze. Even so, bloom is pretty much over now and the two-month fruit set period is underway.

Water relations are very important in the next two months, as this is the period when cell division within the fruit occurs—and it is the number of cells that ultimately exist in the fruit that will determine the genetic potential for ultimate fruit size. It is all important to avoid any semblance of water stress during this period.

According to the Texas Valley Citrus Committee, utilization through March 19 is somewhat ahead of the previous season. Fresh grapefruit shipments are up 3.7 percent; export grapefruit shipments are up 89.4 percent. Shipments of early and mids are up 19.0 percent, while navels are up 30.3 percent. Fresh Valencias are up 8.6 percent.

On the processing side, grapefruit diverted to processing is up 47.4 percent, while oranges diverted to processing is up 69.8 percent. Apparently, no Valencias have been diverted to processing.

For the season to date, dividing the processed volume by total grapefruit volume, processing has accounted for 42.0 percent of total production. Translated into packouts, that means that only 58.0 percent of grapefruit was good enough for the fresh market. At the same time last year, approximately 65.7 percent of grapefruit was packed—but that number dropped to 58.8 percent by the end of the season.

Most in the industry expect that this season’s packouts will decline even more as the season winds down. Most shippers have indicated that they expect to complete harvest soon after the middle of April, with only one expecting to go into May.

No new developments have been reported in Mexico, though it has been reported that a considerable sum of money is being invested in Tamaulipas to combat the disease during this year. Presumably, such funds will be used in scouting, PCR testing and psyllid control, as the disease itself has not been reported there.

There was a minor stir over reports of a new predator in Mexico that could help combat greening. According to Dr. Michael Rogers at Lake Alfred, as reported by Tim Gaver in his March Treasure Coast Citrus Notes newsletter from Ft. Pierce, the “new” insects are green lacewing and Tamarixia radiata. While both are well established in Florida orchards, the levels are insufficient to provide the degree of psyllid control necessary to the management of greening. Moreover, their numbers are reduced by existing ACP control sprays.

Apparently, Mexico is trying to rear these insects for release in groves where the growers cannot afford the ACP sprays. If they are not already spraying for psyllids, then the beneficial insects should thrive, but the caveat is that their populations likely would be too low to provide the necessary level of ACP control to have a very significant impact on the spread of greening.

USDA has recently expanded the quarantine for sweet orange scab to include Florida and Arizona—but California is still not included. The protocols for this disease allow shipments to other citrus-producing states so long as the fruit is subjected to standard packinghouse procedures of washing, fungicide treatment and waxing and is shipped under signed compliance agreements between the packer/shipper and USDA-APHIS-PPQ. For all intents and purposes, only organically-grown citrus is problematic.

One can only wonder how much growers and the industry as a whole lost during the seven-week moratorium on shipments to California/Arizona that Texas shippers imposed on themselves back in November-December. The dollar amount is not limited to just the loss of that market, but also includes the lower prices that resulted from trying to move some of that fruit into other markets. In addition, it appears that the prices did not rebound upward once we started moving fruit back out to California.

Texas Citrus Mutual’s old Mid-Year Meeting has been revamped and will now be known as the Texas Citrus Showcase. It is scheduled for next Thursday, April 7, from 10:00 am to 8:00 pm in the Renaissance Casa de Palmas Hotel in McAllen. It should be interesting, and there is still time to register. Check with the folks at TCM for details.

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

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