- 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.
- Author: Kathy Keatley Garvey
It's Friday Fly Day--and time to post images of a syrphid fly.
Syrphid flies, often mistaken for honey bees, are pollinators, too.
Also known as flower flies and hover flies, syrphids hover over a flower before touching down. "Most species are predaceous, most commonly on aphids or mealybugs," according to the UC Statewide Integrated Pest Management Program. "Some syrphids prey on ants, caterpillars, froghoppers, psyllids, scales, other insects, or mites. About 100 to 400 aphids can be fed upon by each aphid-feeding larva before it pupates, but this varies by the mature size of the syrphid relative to the aphids' size."
They are easily distinguished from honey bees because (1) bees don't hover, and (2) syrphids have only one pair of wings, while bees have two. "Their large eyes and short antenna also give them away, notes Kelly Rourke in a U.S. Forest Service article on "Syrphid Fly (Sphaerophoria philanthus). The absence of pollinium, or pollen sacs, is more difficult to see, but is another difference from a bee. Of the nearly 900 species of flower flies (family Syrphidae) in North America, most have yellow and black stripes."
Several years ago we captured images of a syrphid fly and an Asian lady beetle (Harmonia axyridis) on a rose bush in our Vacaville pollinator garden.
The scenario: Aphids were sucking plant juice on one end and secreting honey dew on the other end. The lady beetle was feasting on the aphids and getting sticky from all that honey dew.
Then along came a syrphid, a female Scaeva pyrastri, as identified by senior insect biosystematist Martin Hauser of the Plant Pest Diagnostic Branch, California Department of Food and Agriculture. It hovered over the lady beetle and then dropped down to lick the honey dew from the beetle's head.
'Twas a happy day for the lady beetle and the syrphid fly, but not so much for the aphids.
![A syrphid fly, a female Scaeva pyrastri, hovers over an Asian lady beetle (Harmonia axyridis). (Photo by Kathy Keatley Garvey) A syrphid fly, a female Scaeva pyrastri, hovers over an Asian lady beetle (Harmonia axyridis). (Photo by Kathy Keatley Garvey)](/blogs/blogcore/blogfiles/88496.jpg)
![The syrphid fly licks honey dew from the head of the lady beetle, which had just feasted on the honeydew-producing aphids on a rose bush. (Photo by Kathy Keatley Garvey) The syrphid fly licks honey dew from the head of the lady beetle, which had just feasted on the honeydew-producing aphids on a rose bush. (Photo by Kathy Keatley Garvey)](/blogs/blogcore/blogfiles/88497.jpg)
- Author: Cindy Kron
- Posted by: Elaine Lander
The spotted lanternfly (Lycorma delicatula) is a new exotic pest that was first detected in Pennsylvania in 2014 and has since moved to other nearby states (Figure 1). Everyone, including home gardeners and retail nursery and garden center employees, can play a significant role in keeping this exotic pest out of California by being the eyes and ears needed for early detection.
Each female produces one to two egg masses of 30 to 50 eggs each. Seedlike eggs are laid in multiple successive rows and covered with a yellowish-brown waxy deposit (Figure 4). The first three immature stages are black with white spots and lack wings. The fourth immature stage is red and black with white spots and have small wing pads (Figure 5).
![Two panel image with spotted lanternfly eggs covered with waxy deposits on left and seed-like eggs with holes where nymphs have emerged on right. Two panel image with spotted lanternfly eggs covered with waxy deposits on left and seed-like eggs with holes where nymphs have emerged on right.](http://ucanr.edu/blogs/UCIPMurbanpests/blogfiles/73241.png)
![Figure 5. The first three immature stages of the spotted lanternfly are black with white spots (L); the fourth immature stage is red and black with white spots (R). Figure 5. The first three immature stages of the spotted lanternfly are black with white spots (L); the fourth immature stage is red and black with white spots (R).](http://ucanr.edu/blogs/UCIPMurbanpests/blogfiles/73242.png)
Adults have a stout yellow abdomen with incomplete black bands and two sets of wings: the forewings and the hindwings. The forewings are a beige-cream color with black spots changing to small black rectangles toward the tips. The hindwings are primarily black and red, with black spots appearing in the red portions. The hindwings are not noticeable when at rest (Figure 6). Adults tend to hop when moving instead of flying.
The spotted lanternfly can negatively affect high value commodity crops in California if it were to become established. In a proactive response to this possibility, researchers at UC Berkeley and UC Riverside are testing biological control agents for this insect.
[Original article published in the Summer 2020 issue of the Retail Newsletter]
We've written about quite a few of the insects that produce honeydew in our blog, so here is a list of the possible culprits that may be causing the mess this time of year:
Aphids
The hackberry woolly aphid is a major pest on hackberry trees. The aphid's honeydew drips all over, leaving behind a sticky mess. Read more about this pest in What's that Sticky Stuff on my Car?
Many other types of aphids suck plant juices and create honeydew on other plants. Visit the UC IPM Pest Notes: Aphids to read more about them, their host plants, damage, and management.
Asian Citrus Psyllid and other psyllids
Psyllids are another pest that produce honeydew, and there is one psyllid in particular that you may have heard about: Asian citrus psyllid (ACP). ACP is infamous for its ability to carry huanglongbing, an incurable disease that kills citrus. Learn how to check your plants for this pest, read the post Invasive Spotlight: Asian citrus psyllid and huanglongbing disease.
Leafhoppers
Read about these small, wedge-shaped pests that hop around and feeds on a variety of plants in our blog article, Leafhoppers on plants.
Mealybugs
This pest is often mistaken for cottony cushion scale, woolly aphids, and even soft scales and whiteflies. They can be found outside in the landscape, but also indoors on houseplants. Learn more about this pest by reading the post New Mealybugs Pest Note!
Scale
Scales can be difficult to identify, since sometimes they may not resemble insects. Once they reach the immobile adult stage, they look like bumps on leaves and stems. The presence of sticky honeydew and sooty mold can be a clue that something is amiss, but this does not occur with every kind of scale. Read the post Scale Insects: Recognizing and Managing for help.
Whiteflies
This tiny pest is fairly easy to identify since it is white and flies around when disturbed. You can find whiteflies on a wide range of host plants, usually living on the underside of leaves. Our post Whiteflies Resource-Newly Updated! has more information.
Ants
Along with the pest, honeydew, and sooty mold, you may also notice an abundance of ants climbing all over your plants. Ants don't produce honeydew, but they are attracted to it. There is an easy solution to this problem you can learn more in the video we discussed in the post Using a Sticky Barrier to Keep Ants Out of Trees.
- Author: Karey Windbiel-Rojas
Around this same time last year, I posted an article called "What's this sticky stuff on my car?".
Well, it's that time of year again when we see the sticky, messy drippings from many different kinds of trees that are infested with a honeydew-producing insect.
I won't repeat the information again, but we've been getting questions from the general public on the droplets and sticky messes they see on sidewalks, plant leaves, and their cars, so I figured it was worth sharing again.
The pests that make this mess will soon go away when the weather changes, but for now, read the article and learn what you can do to reduce the pest numbers and the damage they cause.
![Hackberry woolly aphids. [Credit: Jack Kelly Clark] Hackberry woolly aphids. [Credit: Jack Kelly Clark]](/blogs/blogcore/blogfiles/55422.jpg)