Farm Focus: Citrus Tree Care


Recently Farmer Al wrote about our orchard meeting with Ed Laivo who came out to ID some unusual citrus growing in the orchard. Getting to chat with an expert is always a wonderful opportunity to learn, but being with somebody who is so deeply passionate about their area of expertise is contagious. Ed came out to help us ID some trees that were supposed to be kumquats but turned out to have both pomelos and sour orange. Since they are the wrong kind of fruit we will graft over good kumquat stock later this season. Our citrus orchard is among the oldest at Frog Hollow Farm and we’re excited to take some of his suggestions to improve our regimen and lay a solid foundation to all our new young citrus trees we’ve planted in the last few years. Here are a few of the big citrus tree takeaways from our discussion with Ed:

Good Drainage
Citrus don’t like wet feet (and who does!?) so it is important to make sure they have good drainage. On a farm like ours that means the trees are planted on a berm or small hill so that water drains away from the tree. This helps ensure that oxygen can reach the roots and keep them from rotting during the wet months. Some folks love to keep dwarf varieties in pots so to make sure they drain well it is important to put a layer of rocks at the bottom to ensure good drainage.

Prune, Prune, Prune
As you know from last week’s farm focus, pruning is a big part of winter work at Frog Hollow Farm. The main reasons to prune are to remove dead wood, focus the tree’s energy towards better growth, improve exposure to the sun and air ventilation within the canopy. These last two points are especially important when it comes to citrus trees because of their thick foliage that remains year round. We want air and sunlight to penetrate the canopy to all the leaves for photosynthesis but also to prevent problems like Sooty Mold, a black dusty mold you might see on leaves and fruit of a citrus tree. While it is not detrimental to the fruit themselves the mold can inhibit photosynthesis on leaves and be a sign of deeper issues with pests.

We all know that ants can have a pretty major sweet tooth but did you know that they are farmers, too? They will actually farm little insects like aphids, white fly, leafhoppers and scale which suck energy from their host plant through the leaves. When these pests have surplus of food they will secrete a sweet syrup out called honeydew. Ants love this honeydew and happily care for pests that create it and harvest the sugary nectar from themselves. Another big fan of honeydew are the fungi that causes sooty mold! So if you have a case of sooty mold, you can spray it off but you also have to address the insects causing it by pruning to improve ventilation/sun exposure. If insects continue to be an issue, try spraying with an organic oil for whatever insects you encounter and try using a sticky barrier around the trunk of the tree to prevent ants from setting up shop.

Rootstock Take Over
Have you ever seen a citrus tree produce crazy big thorns and fruit that seems like it is mostly rind instead of flesh? That might mean you’ve got a case of rootstock takeover! Fruit trees are made up of two parts: rootstock, which makes up the lower part of the tree and scion wood, which bares delicious fruit. Most of the time they work together, combining their best traits to be healthy productive trees. Sometimes, especially when stressed, the rootstock can mutiny and take over. When this happens you will see suckers, fast growing branches, come up from the root stock and they will literally take over, sometimes displaying huge thorns and ugly, bad tasting fruit. The fruit can have a ton of seeds, bitter taste and thick skin. If you see these kinds of branches coming up from below the graft line of your tree’s trunk remove them immediately and do your best to address whatever may be stressing you scion wood. If all else fails you can reach out to a local arborist to help graft on new scion wood or replant with a new, healthy tree.