SYMPTOMS AND SIGNS
Olive knot appears as rough galls about 0.5 to 2 inches in diameter on twigs, branches, trunks, roots, leaves, or peduncles (fruit stems).
Olive knot can kill young trees if infected. On older trees, it reduces productivity by girdling twigs and branches and causes dieback. Infection is also associated with an off-flavor of the fruit.
Olive knot disease incidence is generally correlated with rainfall and is more severe in higher rainfall areas. Bacteria survive in galls and as epiphytes on leaves and twigs. As an epiphyte they may be spread on asymptomatic plant tissue.
Olive knot is difficult to kill, it’s best to trim back limbs to remove galls on twigs and branches and burn. Bacteria may be carried from tree to tree by tools and hands. Make sure to clean tools and hands so the disease doesn’t get spread to other trees.
The Olive Shootworm has made its way to Florida.
The worm has been found in Sumpter County feeding on ornamental privet trees, the homeowner noticed the infestation and reported it. Though it has not yet been found on any of Florida's new olive groves it is a major pest problem in Europe and is a major concern for olive growers.
They are coming into Florida from southern Brazil, Bolivia (Sara Department), Peru, Costa Rica, northern
Venezuela, Guadeloupe, Saint Kitts, the Dominican Republic, Haiti and Cuba. Florida counties where they have been found include Broward, Collier, Hillsborough, Miami-Dade, Monroe, Osceola and Sumter.
Inspect your trees, if you see the olive shoot worm take a specimen and place in a small jar filled with alcohol and bring to the extension office or USF for positive identification.
Trim foliage to remove eggs and nests be sure to be thorough, any surviving larvae will consume new growth.
Olive Tree Pests and Cures.
The Armored Scale:
The Armored Scale insect infestation can be life threatening for your tree. They attack as flying bugs or crawling caterpillars then after they hatch, scale are called “crawlers” they attach themselves to a plant by sucking and can do serious damage to the tree. The scale develop an armored oval brown shell
Since you're planning on pressing or curing your olives it not wise to use to use chemicals and insecticides. Once upon a time Dawn was the cure all for insect attacks but now Dawn is not as pure as it once was.
If treating your olive tree in a safe and organic way is the answer that you're looking for then there is a cure but it's a little more work then just spraying pesticides all over your tree. If you're not worried about your fruit you can buy Bayer Tree and Shrub in Lowe's or Walmart and follow the direction on the label.
If organic home remedies are your choice then first cut off the branches that are heavily infested if possible. Make your own castile soap / olive oil soap http://floridaconcerts.org/soap_making_the_old_way_with_woo.htm or buy a NON Detergent fragrance and antibiotic free soap and dilute in water. Dip your sponge in the soapy water and gently rub off the scales as best you can, then spray more soapy water around the tree. You may need to continue treatment until your tree is free of the Scale.
If you are treating more than one tree be careful to wash your hands and tools with alcohol so that you do not spread the the infestation to other trees.