If you have an avocado tree growing in your backyard, you need to be vigilant about a disease that has made a comeback and can destroy your fruit.

It's called Sunblotch Viroid, a microscopic invader that can spread easily.  

CBS Miami spoke with tropical fruit specialist Dr. Jonathan Crane at the University of Florida Research and Education Center in Homestead about the disease. He says a local farmer spotted the disease and notified him, prompting Crane to issue a warning.  

Crane has worked for decades at the research center.

Avocado trees remain vulnerable 

He says that while the laurel wilt fungus wiped out nearly half of the avocado trees in South Florida, the newly planted avocado trees are susceptible to the microscopic invader.

It leaves deep yellow scars on the fruit.

"You can have Viroid in a tree that doesn't show symptoms. It can spread from seeds and rootstock," Crane said.

Growers urged to remove infected trees 

Crane said he tells growers with infected trees, "If it has it they need to properly remove the tree entirely."

David Maes manages Marando Farms and Ranch in Davie, where they grow and sell organic avocado trees.

Farmers recall citrus greening outbreak 

They've had no Sunblotch problem, but he carefully inspects all his trees constantly.

"It's always a concern. You worry you will have to dig up a row," Maes said. "That's what happened with the citrus greening outbreak that happened 15 years ago. Tens of millions of citrus trees had to be destroyed because of a bug."

Experts stress serious threat to growers 

Crane said farmers and home growers should take the Sunblotch threat seriously.

"We have to look out. Because trees can be reduced 14 to 80 percent," he said.

Extension offices offer support 

If you suspect you have an infected tree, contact the UF/IFAS extension office at the following locations:

• UF/IFAS Miami-Dade County 18710 SW 288 St, Homestead (305) 248-3311
• UF/IFAS Broward County 3205 College Ave, Davie (954) 577-6300
• UF/IFAS Monroe County 1100 Simonton St, Key West (305) 292-4501