Monitoring guidelines for macadamia growers
Spotting bug damage
For about two months after initial nut set there is often a natural thinning of macadamia nuts. During this time most nuts fed on by spotting bug will fall off the tree. After this initial two months the nuts will fall less readily as they mature and the spotting bug damage that occurs then is most of the kernel damage found at harvest.
Fallen nuts need to be sectioned to determine the cause of fall. Green freshly fallen nuts of some varieties that have been fed on by spotting bug show dark, slightly sunken spots on the husk. Cells on the inner husk and soft shell collapse and become discoloured in areas surrounding spotting bug feeding points. The kernel may be misshapen and translucent instead of the normal milky white colour. See photo of FSB damage in green nut below.
When the shells are beginning to harden and turn brown, spotting bug feeding can cause small depressions that may be visible on the outer surface of the shell, or there may be only a pin-point mark at the feeding point. Some nut in shell show no sign of injury of the shell though the kernel may be completely or partially damaged. In this case damage can only be detected after nuts are shelled.
Monitoring for green fallen nut
We suggest commencing monitoring for FSB/BSB after fruit set and every two weeks for the next 20 or so weeks (10 monitoring sessions/season). You can monitor more frequently during high pressure periods if you wish.
Procedure:
Print the In Field Monitoring Sheet- Macadamias.
If you have an identified ‘hot spot’ area with high spotting bug damage, randomly select 10 trees (of the same variety if possible) from this area. Then randomly select another 10 (or more if you wish) trees from the rest of the block. Mark these trees to be returned to each monitoring session. If you don’t have an identified ‘hot spot’ area just select 20 trees throughout the block. Using marked trees will help to avoid a bias for trees with more nut drop as you walk through the blocks.
- Count or estimate the total of fresh green fallen nuts per square meter under each marked tree.
- Rate the number of fresh green fallen nut per square meter as either 0 to 5, 6 to 10, 11 to 20, 20 to 30, 30 to 50, 50+ (just estimate when over 20). The values should be converted to a rating- see table at bottom of downloaded monitoring sheet.
- Examine 10 of the freshly fallen nuts from under each tree (if there are that many) and record the number with FSB damage
- Cut open the nut and separate the husk, shell and kernel.
- Examine each part for damage, with spotting bug damage appearing as a brown lesion on the inside of the husk. The developing shell may have crinkled areas.
- If you notice live FSB nymphs or adults whilst monitoring make a note of this in “comments” column.
Monitoring guidelines for avocado, custard apple, lychee, passionfruit and papaya growers
Monitoring procedure
Print the In Field Monitoring Sheet- Avocado, Custard Apple, Lychee, Passionfruit & Papaya
Monitor the crop every two weeks (or more often if you wish) during periods when the crop is susceptible to bug damage. Randomly select then mark 10 trees (20 for passionfruit and papaya), or more if you wish (of same variety if possible) in a hot spot area and 10 trees in the rest of the block (20 for passionfruit and papaya). If you don’t have a distinct hot spot, select one section that might have more pressure than the rest. If you are unsure of ‘hot spot’ or ‘pressure areas’, just select one area in the crop but increase your sample to 20 trees (40 for passionfruit and pawpaw). Return to these trees each time you monitor. By marking trees we are trying to avoid a bias in our selection of trees that will skew what is really happening in the crop.
- Select 10 fruit (or shoots in passionfruit) at random on each tree – you shouldn’t have to pick the fruit. As you inspect fruit look out for bugs and record accordingly. If you want to note if a nymph is small etc do this in “comments”. Remember that, if you are finding nymphs in the crop then the bugs are breeding in the crop.
- Inspect each fruit for FSB damage. Record number of fruit (or shoots) that have old or new damage. In avocados, internal damage is indicated by depressions and damage on the skin but only until full fruit size (maybe 2 months before harvest). Damage caused from then to harvest is mostly not visible until fruit is skinned.
- Add up the each column for each plot
- Transfer the totals to the Monitoring Summary Sheet
