Photo A by Bodil N. Cass
Photos B and C by Tobias G. Mueller
A new pictorial guide can help California growers differentiate between the damages caused by the same pest on different citrus varieties. Comparing the Fruit Rind Scarring That Three Early-Season Pests Cause in Mandarin Species and Sweet Orange was published by University of California Agriculture and Natural Resources.
Early-season insect pests — such as katydids, earwigs and citrus thrips — feeding on newly developing fruit can cause rind scarring damage. Resulting scar damages can lead to the downgrading of fruit in packinghouses, causing huge economic losses for growers. Managing these surface-feeding pests and minimizing their damage is vital to California citrus growers.
Several resources, such as Photographic Guide to Citrus Fruit Scarring, published in 2003, exist to help identify various types of damages. But previous research was mainly based on work with sweet oranges.
With the increasing acreage of mandarins in California, the need for identifying early-season rind scarring damage caused by several pests was recognized. Postdoctoral Scholar Bodil Cass led a group of researchers from University of California Davis in evaluating grower data and conducting experiments at the Lindcove Research and Extension Center. The results of this research are now published as a photographic guide that provides information on how three early-season pests cause damage to mandarin species compared to sweet oranges.
The main findings of the research are that:
- Damages caused by early-season pests are different in Tango and clementine mandarins.
- Katydids do not cause feeding damage on Tango or Afourer mandarins.
- Katydid damage on clementine looks like worm damage on sweet orange. It can cause maturing fruit to split and then drop.
Source: University of California Agriculture and Natural Resources
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