Q.My Plant Has Produced Before. It’s Full Of Flowers But It Seems Something Is Getting The Flowers And Leaving Stems
Should I net it, it appears the green berries are being taken
Certified GKH Gardening Expert
You could try netting, as this is can keep away pests from your elderberries, but there could be other reasons why your flowers and berries are falling off.
Many times, this means that there is too much nitrogen in the soil and not enough phosphorus and potassium. Feeding with both should offset that.
They do their best when there are two, though. Having a second nearby will increase production.
Here are some articles for more information:
https://www.gardeningknowhow.com/edible/fruits/elderberry/elderberries-not-fruiting.htm