- Author: Alison Collin
At this time of year it pays to check any cherry trees for infestations of black aphids, Myzus cerasi. These appear most usually on the tips of the terminal shoots, but also on the spurs and they tend to prefer sweet cherry varieties over the sour ones. Leaves will crinkle and curl over, and become sticky with aphid secretions which in turn encourage the development of sooty mold that in severe cases may render the fruit inedible.
These aphids are shiny black and about 1/8-inch long. They overwinter as eggs on the tree bark and emerge at bud break when they feed on tender shoots, injecting a toxin into the leaves which causes them to curl thus protecting the aphids' increasing numbers.
UC IPM recommends using dormant oil sprays in late winter, and hosing off with jets of water any aphids that are obvious before the leaves curl. As with all aphid infestations keep an eye open for ants traveling up the tree trunk – a sure sign that they have found a good supply of honeydew. Natural predators such as hover flies, lady beetles, and lacewings should be encouraged, but once the leaves curl over, these insects appear not to be so prevalent. At that point water jets really are not effective, either.
On a young tree I have used a bucket of soapy water and bent the stems into it so that the affected regions are well submerged, but this is not possible on a large tree. Sometimes leaves are so infested that ones best option is to simply prune off the infected twigs, placing them directly into a plastic bag, and disposing of it.
Other cultural measures which may help are avoiding lush growth in the spring by not over-watering or using high nitrogen fertilizers. The base of the tree should be kept clear of weeds or other plants that may act as summer hosts.
- Author: Carmen Kappos
For years I thought of garden pests as various insects and small animals but larger animals like deer can do quite a lot of damage to the gardens in our area near the Sierra Nevada Mountains. The University of California Agriculture & Natural Resources, Integrated Pest Management Program (UC IPM) has an excellent online article on deterring deer from browsing on plantings. Check the website for the full discussion HERE.
As the article says; most people enjoy seeing deer in the wild. I know I do, and I enjoy seeing them around my house as well. I also enjoy seeing my ornamental plants flower in the summer. That is a bit of a challenge; just as a favorite plant is about to bloom the tender new growth can be clipped off by this beautiful neighbor.
As the saying goes “good fences make good neighbors,” the UC IPM article states that “physical exclusion is by far the best and most reliable way to protect gardens, orchards, and ornamental plantings from deer. “ Fencing is discussed in detail, but in my small patch of a garden, a full fence is impractical. Individual plant protectors, also mentioned in the article, are a much easier way for me to enjoy flowers in my yard.
The left photo shows some scarlet penstemmon, a favorite of mine and the hummingbirds. Penstemmon in my yard is often browsed by deer but, so far, this year the plants with individual protectors are untouched. The fact that any of my plants are blooming at all is reason enough for me to celebrate. Seen in the photos, the easily constructed plant protectors are surrounding a daylily and a native Gilia blooming in the background. The Gilia got clipped by deer early in the season but after the cylinder was added I had no further damage, even though the top is open. The right hand photo shows the easily constructed plant protectors are surrounding a Day Lily and a native Gilia blooming in the background. The Gilia got clipped by deer early in the season but after the cylinder was added I had no further damage, even though the top is open.
In past years I have also made larger enclosures to surround an entire planting bed with good results. Dustin Blakey, our local Cooperative Extension farm advisor described that if the enclosure is small and tall enough that the deer would not be able to move freely inside, then they likely won't jump in. The largest individual enclosure I've made is two feet by three feet and it worked well. It also needs to be small enough or tall enough that they won't just dip their heads in and browse.
For a real challenge, grow a vegetable patch near our wild neighbors. I stopped by the community garden in Lee Vining recently and got a tour of the many ways they exclude garden pests. The perimeter fence keeps out rabbits, but is not tall enough to keep out deer. To keep the deer off their plants, they enclose the raised beds in wire mesh, and keep adding on segments as the plants grow taller. Also, as you can see from the photos, shade cloth on top of some raised beds keep the deer off and a little opening can still allow bees and other pollinators in.
The Lee Vining Community Garden is celebrating twenty years of growing this summer. Congratulations on producing food while living with and enjoying our wild neighbors!
- Author: Dustin Blakey
We have a lot of trees in our area related to poplars: aspens and cottonwoods are two common examples. Most species in this genus (Populus) are subject to infestations of the poplar bud gall mite. I've seen a couple samples each summer in our area.
The gall mite causes strange growths called galls mostly on buds of last year's growth. Cottonwoods and poplars seem to get it often, but some species and cultivars are resistant. It's not usually fatal. In some cases the infestations are bad enough to cause real problems and branch dieback.
This is what it looks like:
The pest in this case is an eriophyid mite. For the curious, pictured below is the bindweed gall mite. It's a relative that looks about the same. Honestly, it doesn't matter what the pest looks like because you would need a powerful microscope to see them. They're very tiny! (Much smaller than spider mites.)
Heavy infestations can kill branch tips and set a tree up for future problems. Small infections are largely harmless. It's been my observation that most galls occur on the lower portion of the tree.
If you check out the UC IPM website, it just throws its hands the air unhelpfully and says don't worry about eriophyid mites. It's right. There really isn't a lot a homeowner can do about it. For this pest, pruning off the galls often helps the next year if you get them all—and there aren't too many.
Spraying doesn't often work. Although it would make you feel like you were doing something, I would probably try to talk you out of it.