A Conditional Branch cannot refer directly to the quantity of an item, but the quantity can be copied to a variable, and the Conditional Branch can refer directly to that.
Before your Conditional Branch, insert a Control Variables (tab 1). In the Variable pane, select Single, click the button next to Single, select a variable that you're not using for anything else, and name it "Berry Count". In the Operation pane, select Set. In the Operand pane, select Game Data. Click the button next to Game Data to open the Game Data dialog. In the Game Data dialog, select Item. Click the button next to Item and select your item "Berry". The Game Data dialog should look like this:
and the Control Variables dialog should look like this:
In your Conditional Branch, don't select Item (tab 4). Select Variable (tab 1), set the variable to "Berry Count", set the comparison to ≥, and set the value to constant 35. The Conditional Branch dialog should look like this:
and your event code should look like this: