Table Olives a new target!

Research by Summerland Olive Products into table olive crop losses of up to 95% from ineffective control of Anthracnose and other Fungal disease has revealed a Bug is causing a significant part of the initial problem. Anthracnose and other Fungal diseases appear to be secondary infections at sites where Bug damage has occurred.

The Green Vegetable Bug (GVB), Nezara viridula, has been positively identified by an Entomologist at DPI Alstonville from samples of the Bugs and damaged olives in groves from Boonah in Southeast Queensland, Tabulam, Yorklea, Grafton in the South and Tamworth in the West NSW.

Varieties sampled were Manzanillo, Mission, Kalamata, Jumbo Kalamata, Nabtamri and Azapa (both green and black) from 2007, 2008 and 2009 seasons.

The GVB pierces the fruit and sucks out juices from the olive, then repeats the process up to thirty times on a single olive. Olives are most susceptible from fruit set to 40 days from fruit set. The small piercing is not visible to the naked eye until the olives start to ripen or are picked and soaked in brine for a day. If left to oxidise the piercing become visible on the olive.

gvb22-fruit-damage-300x228 — Bug Damage on Green Jumbo Kalamata olive

These piercings provide entry points for fungal rots such as Anthracnose. Olives subject to attack appear to ripen early as the fungal rots grow. At this stage, fungal sprays appear ineffective to control the fungus resulting in crop losses.

By controlling the GVBs initially fungal sprays will become more effective against Anthracnose and other fungal diseases.

The preferred sampling for the GVB is Beat Sheeting; this involves laying a sheet under the tree and shaking a branch to dislodge the bugs, which fall into the sheet below. Also look for egg rafts and bugs in the trees. The sticky pad type sampling appears ineffective in sampling trials.