- Author: Anne Schellman
- Author: Ed Perry
- Why are the leaves on my orange tree turning yellow?
It's common for citrus tree leaves to turn yellow in winter*. Fertilize to provide the tree with nutrients now, then watch as leaves green up in spring. Avoid fertilizing in fall, which encourages new growth favored by pest and can leave the tree susceptible to frost injury.
- How do I know if my oranges are ripe/when should I pick my oranges?
You don't have to pick all your oranges once they ripen. In fact, the best place to store oranges is on the tree, where they stay fresh! Pick as needed, unless temperatures below 28 F are predicted, then you'll want to harvest.
- What is this pest?
Scales and whiteflies suck plant juices and weaken the plant. Ants do two things:
- Protect pests from predators like ladybugs, parasitic wasps (very tiny wasps) and lacewings.
- “Harvest” honeydew (a sticky sugary substance excreted by these pests) for food, in a symbiotic relationship that does not include the gardener.
- Why are my oranges splitting?
The reason this happens is not well understood, although it's often related to changes in weather conditions. However, allowing the soil to dry out too much between irrigations is believed to result in increased splitting. Make sure your tree has a constant supply of moisture by watering monthly during the dry season.
- When should I prune my orange tree?
When pruning deciduous trees like peach, plum or cherry, after leaf drop, don't be tempted to prune citrus! Citrus trees are evergreen and require little if any pruning except to control size. If you'd like to keep a new citrus tree under 5 feet tall, you can carefully prune it in spring to manage the height. This way, you won't need a ladder to pick fruit again!
Avoid pruning in fall or winter, which encourages new growth favored by pests and can leave the tree susceptible to frost injury.
*if your tree leaves turn yellow and it's not winter, this may be a different problem.
[From the UC IPM blog Pests in the Urban Landscape]
1. Aphids
These insects may be small, but they can quickly build up large populations. With many different species in California that feed on vegetables, flowers, fruit trees, and woody ornamentals, aphids are a common sight in landscapes and gardens. Year after year, aphids continue to hold the top spot. Learn more about aphids and their management in Pest Notes: Aphids.
2. Fungus Gnats
3. Thrips
Another tiny insect sometimes found on houseplants, thrips are slender insects about the size and shape of a dash printed in a newspaper. They suck out the cell contents, leaving a discolored speckling on leaves or stunting plant growth. For more about thrips monitoring and management, visit our Pest Notes: Thrips.
4. Mealybugs
If you've found soft, oval insects that are white in color with wax filaments on your indoor or outdoor plants, it is likely you have mealybugs. These wingless insects are often found in clustered colonies. In yards and gardens, handpicking, pruning, or high-pressure water sprays can reduce populations. For small infestations indoors, spot treatments may help reduce populations. For houseplants with severe infestations, consider disposing of the plant. Find additional information in Pest Notes: Mealybugs.
5. Carpet Beetles
6. Peach Leaf Curl
Peach leaf curl can affect the blossoms, fruit, leaves, and shoots of peach and nectarine trees. The symptoms of the disease first appear in spring, when distorted red foliage emerges. However, focus management for nonresistant varieties in the late fall and early winter, after leaves drop. Read more about this disease in our Pest Notes: Peach Leaf Curl.
7. Clothes Moths
New to the top ten list this year were clothes moths. These pests tend to hide when disturbed, so you may not realize you have an infestation until after the moths have already damaged fabric, fur, or feathered items. Some clothes moths make webs while others are casemaking moths. Regularly monitoring and cleaning clothing and storage areas can help prevent or reduce infestations. Find more identification and management information from Pest Notes: Clothes Moths.
8. Springtails
9. Whiteflies
Whiteflies are not actual flies but are tiny insects that are often found on the underside of leaves, feeding on the phloem of many different plants. Certain species can cause significant loss in vegetable gardens; other species found in fruit trees are less damaging. Both adult and immature whiteflies also attack houseplants. Management information can be found in Pest Notes: Whiteflies.
10. Scales
Scales are small, legless insects that look like tiny scabs on the stems, leaves, or fruit of plants. While some scale species can weaken a plant when abundant, other species do not appear to damage plants at all. Think you have a problem with these insects? Visit our Pest Notes: Scales for identification and management options.
/h3>/h3>/h3>/h3>/h3>/h3>/h3>/h3>/h3>/h3>- Author: Denise Godbout-Avant
Aphids
According to UC Integrated Pest Management (UC IPM), aphids are small, soft pear-shaped bodied insects with long legs and antennae, with slender mouthparts used to pierce stems, leaves and other tender plant parts to suck out plant fluids. The site recommends first attempting to control aphids by washing them off with a gentle stream of water. I did this over several mornings and evenings, with my hose set on fine spray, washing both the top and underside of the leaves. After about a week, I still had quite a few aphids, so I sprayed an insecticidal soap, making sure I covered both the top and bottom of leaves. Aphids produce many offspring, so they required an additional treatment.
Scale Insects
Soft scale is a sucking insect, appearing as tiny dots on the leaves or stems of a plant. They can grow up to ¼ inch long and have a smooth, cottony or waxy surface. They feed on the sap of the plant and excrete sticky honeydew, which can attract ants. Mine were brownish-yellow with a waxy color, usually appearing on the underside of the leaves.
I removed badly damaged leaves, checked undersides of the leaves for the scale and scraped off any scale I found using a wet Q-tip. I also checked my other two plants and occasionally found a scale or two on them, scraping them off also. I repotted the infested plant with potting mix. Over time I was able to completely get rid of the soft scale.
Whiteflies
My Buggy Summer Summary
It has been an educational summer learning about these insect pests and dealing with their infestations. I'm gratified I've been able to manage them using less toxic pesticides that are less harmful to beneficial insects and the environment. You can learn more about less toxic pesticides such as insecticidal soaps and oils by visiting the UC IPM website or by watching this video.
Denise is a UCCE Stanislaus County Master Gardener.
[From UC IPM's Pests in the Urban Landscape Blog]
At some point, all of us encounter a pest in our home, garden, or landscape. But you're not alone! UC IPM publishes Pest Notes – a series of more than 150 papers reviewed by experts in the field – to provide science-based information about pests and their management.
These ten Pest Notes were the most frequently viewed online in 2019, with more than 330,000 total pageviews. While it's not a contest, we like to think these are the winners of 2019's most popular pests.
1. Aphids
These small, soft-bodied insects can multiply rapidly, especially in warm weather. Many species exist in California, feeding on vegetables,flowers, fruit trees, and woody ornamentals. Their sticky honeydew encourages growth of sooty mold, while their feeding can distort growth or transmit viruses from plant to plant. Managing ants and supporting natural enemies are two ways you can reduce aphid damage. Learn more about aphids and their manaent in the Pest Notes: Aphids.
2. Thrips
Thrips are tiny, slender insects about the size and shape of a dash printed in a newspaper. Some are beneficial predators that feed on other insects and mites. But most feed on plants, sucking out the cell contents, leaving a discolored speckling on leaves or stunting plant growth. An integrated approach is recommended for management, incorporating good cultural practices, natural enemies, and least-toxic insecticides if needed. For more about thrips monitoring and management, visit our Pest Notes: Thrips.
Peach leaf curl can affect the blossoms, fruit, leaves, and shoots of peach and nectarine trees. The symptoms of the disease first appear in spring, when distorted red foliage emerges. However, focus management for nonresistant varieties in the late fall and early winter, after leaves drop. Read more about this disease in our Pest Notes: Peach Leaf Curl.
4. Scales
Scales are small, legless insects that look like tiny scabs on the stems, leaves, or fruit of plants. While some scale species can weaken a plant when abundant, other species do not appear to damage plants at all. Think you have a problem with these insects? Visit our Pest Notes: Scales for identification and management options.
5. Fungus Gnats
This pest was surprising to find in this year's top 10. Fungus gnats are small flies that often infest soil and potting mixing, emerging from indoor houseplants and becoming a nuisance. The larvae, or immatures, can damage roots and stunt plant growth when present in large numbers. If you do see these flies flitting about, sticky traps may be effective in reducing the problem. However, the presence of gnats and decline of house plants are more commonly due to too much or too little water and improper soil conditions. More information on these frustrating flies can be found in our Pest Notes: Fungus Gnats.
6. Mealybugs
If you've found soft, oval insects that are white in color with wax filaments on your plants, it is likely you have mealybugs. These wingless insects are often found in clustered colonies on indoor and outdoor plants. In yards and gardens, handpicking, pruning, or high-pressure water sprays can reduce populations. For small infestations indoors, spot treatments may help reduce populations. For houseplants with severe infestations, consider disposing of the plant. Find additional information in Pest Notes: Mealybugs.
In residential areas, this not so mysterious marsupial will take up residence under porches, decks, garden sheds, attics, and basements. Opossums are nocturnal omnivores, foraging for fruits, nuts, plants, insects, snails, and even small mammals such as mice. In addition to being a nuisance in residential areas, they carry various diseases that can be transmitted to humans including tuberculosis, spotted fever, and typhus. The best control for opossums is to screen or block access to areas where they may den. You may also choose to hire a professional wildlife control operator to trap and dispense of any opossum visitors. Pest Notes: Opossum has more on the biology and management of these animals.
8. Carpet Beetles
Carpet beetle adults are typically brought into the home on cut flowers or when they fly in through open doors, windows, or holes in screens. The immature beetles feed on animal products such as wool, silk, leather, fur, and hair. Regular cleaning of rugs, upholstered furniture and closets as well as eliminating accumulations of lint, hair, and other debris is an important preventive measure. Check out the Pest Notes: Carpet Beetles for more preventive and management methods of these pests.
9. Ground Squirrels
Ground squirrels are troublesome rodents found throughout most of California. Their network of burrows can be extensive, damaging trees, lawns, and structures. Ground squirrels can also damage many food-bearing and ornamental plants in yards and gardens. For legal management methods, see our Pest Notes: Ground Squirrels.
10. Whiteflies
Whiteflies are not actual flies but are tiny insects that are often found on the underside of leaves, feeding on the phloem of many different plants. Certain species can cause significant loss in vegetable gardens; other species found in fruit trees are less damaging. In home gardens, reflective mulch can repel whiteflies and yellow sticky traps can reduce numbers of high infestations. Additional management information can be found in Pest Notes: Whiteflies.
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