Citrus greening, the disease that has caused significant crop losses in Florida, has been found in Texas.

Positive samples were found on trees in San Juan, in Texas’s Rio Grande Valley, according to the Texas Department of Agriculture. Texas Citrus Mutual learned of the findings Jan. 13, Ray Prewett, president of the Mission-based organization, wrote in a Jan. 16 e-mail to growers.

Because of the finds, the department issued a temporary emergency quarantine in a five-mile radius around a point in San Juan. Citrus nursery stock in the quarantined area may not be shipped outside the area. Fruit may be shipped out, but it must be free of leaf material and debris.

The quarantine, effective Jan. 13, expires Jan. 20.

Citrus greening, first identified in 2005, has destroyed hundreds of thousands of acres of citrus in Florida. It also has been found in Georgia, South Carolina and Louisiana.

The greening finds will not have much of an effect on the 2011-12 season, said Mike Martin, president of Mission, Texas-based Rio Queen Citrus Inc.

“The crop is more than made,” Martin said Jan. 17. “There’s less than 40% remaining. We think it will have very little impact on this season.”

As for next season, it’s impossible to tell at this point, Martin said. As of Jan. 17, officials had no way of knowing how far greening had already spread in Texas.

“It could be a big area, it could be small,” he said. “We don’t know.”

While Rio Queen had the option of shipping out of the quarantined area if it removed leaves and other plant material from fruit, the company decided to cease harvest in the area, pending further notice.

The Texas industry knew greening was coming, Martin said, but it was still a shock.

“Experts had been saying it was not a matter of ‘if’ but a matter of ‘when,’ but it’s somewhat demoralizing,” he said.

Asian citrus psyllids, the pests that carry citrus greening, had been found earlier in Texas, but they tested negative for greening. Psyllids testing negative also have been found in citrus-producing states California and Arizona.