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A blog by the UC Master Gardeners of Stanislaus County
UCANR: Promoting healthy people and communities
Use taste, rather than rind color, to determine when to harvest citrus
  • Author: Ed Perry
Published on: January 3, 2023

Orange fruits hang from a tree with deep green leaves.
Mandarin. T. Williams, Roose lab, UC Riverside.
Knowing when to harvest any citrus fruit involves the question of its degree of maturity. Technically speaking, there is no ripening process in citrus fruits and no such thing as "tree ripe" fruit. Citrus fruits pass from immature to mature and finally to an overmature condition while remaining on the tree, but the changes are slow and spread over several months. The only way to determine maturity is to taste the fruit.

Fruit color is a poor indication of ripeness, because many fruits have fully colored rinds a long time before they can be eaten.

Don't expect citrus fruits to increase in sweetness or ripen more fully once you've picked them, as do peaches and some other fruits. When picked at any stage of maturity, citrus fruit does not change after picking, except that it may decay or slowly dry out.

Two yellow fruits hanging on a tree showing browning on the rind of one of the fruits.
Brown rot on lemons, Jack Kelly Clark, UC IPM.
Unless damaged by frost, citrus fruit keeps longer on the tree than if picked and stored. Once you begin to harvest, pick fruit from the lower branches first, leaving the high fruit until later in the season. There are two reasons for this; one is that frost is often more severe near the ground, so low hanging fruit is more likely to be damaged when the weather is cold; secondly, a fruit-rotting fungus disease called brown rot may splash from the soil, where it lives, onto fruit hanging low in the tree. Brown rot can penetrate unblemished citrus fruit rind, unlike other decay organisms which require a break in the rind to cause injury.

When you're picking citrus fruit that you plan to store for awhile, be careful not to bruise or break the skin. Fruits that are cut or scratched during harvesting will rot fairly quickly in storage. Citrus fruits with perfectly sound skin are fairly decay proof, and will last in cool, moist storage for several weeks (38 to 48 degrees F, 85 to 95 percent relative humidity). Under dry conditions at room temperature, fruits develop off flavors and shrivel within a week to 10 days.

Ed Perry is the emeritus Environmental Horticultural Advisor for University of California Cooperative Extension (UCCE) in Stanislaus County where he worked for over 30 years.

Public Value: UCANR: Promoting healthy people and communities
Focus Area Tags: Yard & Garden
Tags: brown rot (2), citrus (12), frost (4), fruit (10), harvest (5), maturity (1), Perry (14), ripeness (1)
Comments: 0
UCANR: Safeguarding abundant and healthy food for all Californians
Caring for Citrus in Fall
Published on: November 8, 2021

Two yellow lemons with a brownish tinge towards the bottom of the fruit.
Infestation of brown rot on lemon. (Jack Kelly Clark)
 [From the UC IPM blog Pests in the Urban Landscape] 

Citrus trees need care throughout the year, including cultural practices to keep trees healthy and pest management. During the fall season, several pests can attack citrus trees in many California regions. 

Brown Rot

Monitor for this disease by checking for damaged fruit on your tree, as well as fruit in storage. Sometimes affected fruit develops a pungent odor and can ruin fruit held in storage. See the UC IPM web page on Brown Rot to learn more.

A zigzag line showing a tunnel made by a leafminer larva.
Winding citrus leafminer tunnel on a leaf. (David R. Haviland)
Citrus Leafminer

If you see what look like small “tunnels” on your citrus tree leaves, your tree might have citrus leafminer. The adult stage of this pest is a small, light colored moth; the larval stage feeds and develops inside the leaves of young citrus and other closely related plants.

Citrus leafminer rarely causes problems for mature trees, however, it can seriously damage very young trees. Read the UC IPM Pest Notes: Citrus Leafminer for recommendations for prevention or management.

Snails and Slugs

Snail on bottom of an unripe citrus.
Snails on citrus. (Jack Kelly Clark)
Snails and slugs are attracted to citrus trees and can feed on foliage and fruit. A good sign that these pests are the perpetrators of tree damage are the silvery trails of slime along the ground or on tree leaves, or even see the snails or slugs themselves. For management tips, read the UC IPM Pest Notes: Snails and Slugs.

Asian Citrus Psyllid and Huanglongbing

You may have heard of the Asian citrus psyllid (ACP) and the deadly disease huanglongbing (also called citrus greening) that has been featured in the news. This disease doesn't pose a threat to humans or animals, but is deadly to citrus trees. Once a tree develops huanglongbing, there is no cure, so for this disease prevention is key.

Small, light green leaves showing distortion and very tiny insects.
Adults and nymphs of ACP attacking new leaves. (Michael. E. Rogers)
Stopping this serious citrus pest will require everyone's help. To learn more about the psyllid and the disease, as well as what you can do, visit the UC IPM Pest Notes: Asian Citrus Psyllid and Huanglongbing Disease.

UC IPM Web Site

For information on managing other citrus pests in the garden, see the UC IPM webpage on Pests in Gardens and Landscapes: Citrus.

Public Value: UCANR: Safeguarding abundant and healthy food for all Californians
Focus Area Tags: Yard & Garden
Tags: brown rot (2), citrus (12), fall (8), leafminer (1), slugs (1), snails (1)
Comments: 0
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