A volunteer is preparing a piece of scion wood to be grafted using a saddle graft. The knife isn't sharp enough because you can see the bark torn and splayed down the cut. A grafting knife must be kept razor sharp and should never be used for any other purpose.
Our first field trip is this Saturday for the California Rare Fruit Growers meeting in Santa Monica - I'll be at the Garden no later than 7:30 to get scion wood for those who would like to have scion wood to exchange at the meeting - see the post below regarding the process to collect scion wood and keep it. We probably won't do any grafting until the 1st of March so you'll need to store the scion wood in the fridge.
NO CLASS THIS SUNDAY - it's a University Holiday. Seems likely to rain anyway.
If you need more information than is available here, call or email me.