Now is the time for the gross stuff – critters. Critters of the animal, insect, fungus, bacteria, and heavens know what other kind, variety. I wouldn’t be a good steward of the olive industry if I didn’t mention them.

Agriculture is fraught with peril. Not enough rain, too much rain, and in the case of the olive tree too much standing water. Olive tree roots hate to stay wet. Not enough sun, not enough cold, or too much cold and the bark will crack, weakening the olive tree. Like all other plants olive trees have environmental susceptibilities. But then, there are the pests and diseases too.

I know the environmental part is very important, but whenever someone asks me where they can get an olive tree for their yard, I can’t help but share cautionary tales about the pest and disease perils that their sweet little tree can potentially visit upon the existing and fledgling U.S. olive industry. I let them know it is their duty to their local growers and those who want to eat local produce not to have their own tree. What a worry wart, you say? You bet.

Let me explain. Joe, my brother, lives in Florida. He planted an olive tree next to his pool. Nice. Florida is an agriculture state that has laws in place to deal with commercial crop and non-commercial infestations. Florida is authorized to treat not only commercial crop infestations but non-commercial too, so long as the commercial crop is jeopardized. If olive fruit fly were to alight in Florida, Joe’s tree can be sprayed along with the commercial crops in his state. I live in a state just next door with different laws. Good luck getting on Granny’s property to treat her tree. Therefore, I worry. Georgia has a fledgling olive industry that I don’t want to see die out prematurely or affect the one we have – in California.

Today our featured pest is the olive fruit fly, bactrocera oleae. The olive fruit fly is the most serious threat to the U.S. olive industry to date, and in the U.S. it has no known predators or parasites. Now that the U.S. olive industry is expanding into other states, each with different laws, the olive fruit fly is an important insect to get to know.

In 1998, the olive fruit fly was discovered in southern California. Exactly how it arrived is not certain, speculation is that it was brought from France. By 2002, the southern California visitors had travelled the state and were everywhere. For such a tiny little fly, that was some fast moving. California’s olive industry was in peril, and as we know today, some folks in the industry did not survive.

When the olive fruit fly invaded, it was a good crop year, and eradication was a problem. California has a significant number of trees on private lands and in roadways. Those trees acted as “reservoirs for reinvasion into treated orchards” (Collier, T.R. & Van Steenwyk, R.A. (2003) see below for link to article).

The olive fruit fly is common in the Mediterranean region and in the Mediterranean it has natural parasitic foes. We do not have them in the U.S., however, there are studies being conducted into parasitic alternatives, like a Pakistani olive fruit fly known as psyttalia ponerophaga.

In the mean time, the olive fruit fly is under control in California. Research is still underway for ways to effectively eradicate an infestation or keep one from happening at all.

Here are links to two documents regarding the olive fruit fly. The first is “Olive Fruit Fly” by Paul Vossen, Lucia G. Varela, and Alexandra Devarenne. The second is a research article entitled “Prospects for integrated control of olive fruit fly are promising in California” by Timothy R. Collier and Robert A. Van Steenwyk.

May the sun shine through your branches.

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