Missing Oranges fixed!
While troubleshooting my broken MultiTab on this forum, I stumbled on the easy path to fix the missing oranges problem as well. The solution is a modified (and much faster) version of Trip's suggestion about deleting DCBackup and reinstalling all store content. The culprit is the ccmerged.package file within the DCBackup folder.
Simone23's post in this thread,
http://www.carls-sims-3-guide.com/forum/index.php/topic,10460.100.html, leads to NonaMena's solution here:
http://nonasims.wordpress.com/tag/multitab-6000/. Nona has a wonderful detailed explanation of the steps to repairing and reinstalling premium content, and if you read through to the end of her page before taking action, she also provides a perfect solution for the laziest among us (me!) by offering her good ccmerged file for download. I simply emptied the contents of DCBackup, pasted her good file in, and voila, oranges!
Thanks to NonaMena for the excellent explanation, detailed instructions and especially for providing a valid ccmerged file to download, and thanks to Simone23 for linking to her site. I've now got oranges! (and a functioning MultiTab, too)
I guess this answer could go into the technical help instead, but I wanted to be sure people know that the missing oranges problem isn't with Grandpa's Grove specifically. And as KTK10 mentioned, the tractor is a blast. What a boon for gardeners.