Danielle S. Williams | Gardening in the Panhandle

Citrus Leafminer in Dooryard Citrus

by Danielle S. Williams | May 20, 2019

Citrus leafminer injury. Photo: James Castner

Spring is in full swing and citrus trees have begun actively flushing. With the new flush comes an array of insect pests. One of the most common being the citrus leafminer. The citrus leafminer is a small white moth, about 2.4 mm in length. It is more easily detected during its larval stage by the serpentine larval mines it produces on the underside of citrus leaves.

Citrus leafminer adult. Photo: James Castner

The larvae of the citrus leafminer feed on the new growth or flush of citrus causing serpentine mines to form under the leaf cuticle. This can result in leaf curling and distortion. Citrus leafminer injury to foliage can stunt the growth of young trees and in areas where the citrus canker pathogen is present, provide an opening for infection.

Distortion and leaf curling caused by citrus leafminer. Photo: Danielle Sprague

The term ‘flush’ is commonly used to describe the new foliar growth between bud break and shoot expansion. Citrus trees usually have several flushes per year, depending upon cultivar, climate and crop load. Generally, most citrus cultivars in our area have around three flushes. The main flush is the spring flush in late winter/early spring. Following that, two additional flushes occur around the end of June and late September.

Citrus leafminer on young flush. Photo: Danielle Sprague

Adult leafminers require the new citrus flush for development. Eggs are laid within the flush. After two to ten days, the larvae emerge and feed causing the mines to occur. Larvae are protected within the leaf and therefore difficult to control. Pupation occurs within the leaf mine and takes anywhere from six to 22 days, depending upon temperature. Adults emerge around dawn and are most active in the morning and evening. In Florida, one generation of citrus leafminer is produced about every three weeks but populations increase when citrus trees are flushing.
In Florida, several natural enemies assist with reducing citrus leafminer populations. Studies have shown that predation from natural enemies can reduce leafminer populations by 90%. Primary predators of citrus leafminers include ants, lacewings and spiders. A parasitic wasp, Ageniaspis citricola was introduced into Florida and has become established. The parasitic wasp attacks the immature stages of citrus leafminer. Ageniaspis citricola can be requested and obtained for free from the Florida Department of Agriculture and Consumer Services (FDACS). Because it is a specialized parasitoid of the citrus leafminer larval stage, it should be released only when mines start to become visible on flush.
Citrus leafminer can be difficult to control with insecticides due to the fact that they are within the leaf and protected. Applications of insecticides require proper timing and may require repeat applications. For a full list of insecticides, contact your local Extension Office.

For more information on citrus leafminer, use the links to the following publications:

Citrus Leafminer, Phyllocnistis citrella Stainton (Insecta: Lepidoptera: Phyllocnistinae)

Citrus Leafminer Control – UGA

Planning the Garden: Crop Rotation

by Danielle S. Williams | Mar 26, 2019

With spring on the horizon, many of us are planning or have already began to plant our spring gardens. If you’re still in the planning process like me, one very important thing to consider is the importance of crop rotation in the garden. Crop rotation is a concept that’s been used by farmers for many years but it’s a concept that gardeners need to adopt as well!

What is crop rotation?

Crop rotation is a method used to reduce insect pests, disease and manage soil fertility by changing the planting location of vegetables within the garden each season. Each vegetable is grouped into a plant family. Vegetables in the same plant family typically are able to harbor the same kinds of insect pests and diseases, and have the similar nutrient requirements. When vegetables belonging to the same plant family are planted in the same location over and over again, pest populations can build up and productivity of the garden decreases. In addition, fertility issues can arise from planting the same crops, in the same area over again. Since different crops require different types and amounts of nutrients, crop rotation can help even out the loss of soil nutrients.

List of common vegetable families.

How should I plan for crop rotation in my garden?

First, consider the vegetables you would like to grow this season then group them by their families. Vegetable crops in the same family should NOT be planted in the same area year after year. For example, if squash is planted in a bed or one area of the garden one year, cucumbers or watermelons should not be planted in the same area of the garden the following year because these plants belong to the same family (Cucurbitaceae).

Divide your garden according to the number of plant families you want to grow. This could be in rows or even separate beds. From there, you will want to think about your ordering sequence. For example, if you are planting a legume (beans or peas) that fixes nitrogen back into the soil this spring, you’ll want to plant a heavy feeding crop like broccoli this fall. Heavy feeding crops can be followed by light feeding crops such as carrots or onions. Be sure to keep a gardening journal as a reminder of what is planted each year and season.

Crop rotation is one of the most effective methods we have to manage the many pests and diseases we have here in Florida. If you’re struggling with a particular pest or disease in your garden, consider using crop rotation to help manage it. For more information on crop rotations for the home garden, contact your local extension agent.