Shoot strike monitoring in peach and nectarine

How to monitor for shoot strikes in peach and nectarine: video and transcript

In this video, Farm Advisor Janine Hasey demonstrates how to monitor for shoot strikes in peach and nectarine orchards.

(Janine Hasey speaking)

Hi. I'm Janine Hasey, farm advisor with UC Cooperative Extension in Sutter and Yuba counties. I'm here to show you how to monitor for shoot strikes in peaches and nectarines found in the peach and nectarine pest management guidelines. This research-based method is much faster than the older method of cutting out all shoot strikes from a tree.

You'll need a monitoring form and a counter. Also bring along a pole-pruner for the last sampling step.

Shoot tips are killed when oriental fruit moth and peach twig borer larvae bore inside them, resulting in shoot strikes or flagging.

You can see drooping, green leaves at the top of the shoot on a new shoot strike. Newer shoot strikes are more likely to contain larvae than older ones. Older shoot strikes dry up and turn brown.

Here you can see shoot strikes that are still green. This is an older shoot strike and if you look carefully [at] the base, this is where the larvae bored in.

Don't confuse plant bug feeding damage with moth larval shoot strikes. Plant bugs like Calocoris do not tunnel into the shoot, but their feeding breaks the shoot so that the tip droops especially inside the tree canopy. Do not count these strikes.

To monitor, select trees randomly starting from an outside tree and moving toward the middle of the orchard to get a good cross-section of the block.

Pick a starting point at each tree and circle it looking up, down, and inside the tree, counting all the shoot strikes. Record the number of shoot strikes you find on a tree before moving to the next one.

Once you inspect 5 trees, record the average strikes per tree. If you are approaching the treatment threshold, an average of 3 strikes per tree, sample a couple more trees to verify you've reached the threshold.

Once the threshold is reached, apply an insecticide whether the orchard is using pheromone mating disruption or not, at the proper spray timing.

Using the pole-pruner or shears, cut off a few of [the] newer strikes and pull the shoot apart to look for the larvae.

Identify whether Oriental fruit moth or peach twig borer is in your orchard. Knowing what species you have is important for spray timing and to select the most effective insecticide.

Peach twig borers have alternating light and dark bands, whereas very young Oriental fruit moth larvae are white and turn pink with brown heads as they mature.

For more information, consult the Pest Management Guidelines for peach or nectarine at www.ipm.ucanr.edu.

(Punjabi transcript by Gurreet Brar)

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