- Author: Mark P Bolda
- Author: Yu-Chen Wang
A few weeks ago Mark got a call from a person who was wondering why a fungus that we work with, he believes it was Zythia ,also has another name, that being Gnomonia.
There's quite a bit to sort out here, and so please follow us here.
This is a topic very much worth some discussion as renaming of things in our day does carry some emotional weight to it, indeed Mark suspects this person was wondering if these two names weren't part of such a scheme. As any bird watcher knows, the birder community has been rocked in recent times by the plan of the American Ornithological Society to rename some 80 birds because the current names are seen as offensive by some (which we are not going to publicize here).
The double naming, also known as "dual nomenclature", of many fungi, which refers to sexual and asexual stages of the same fungus, is nothing like this however. The way this system of two names for the same fungus came about was that the botanist Karl Linnaeus, who in the 18th century began to formalize the system of naming organisms, saw fungi simply as plants and concluded from there that fungal spores were like seeds. And so it followed, in the mind of Linnaeus, that since one species of plant equaled one single type of seed, it would only follow that one species of fungus should equal one type of spore. The problem that we now know is that the asexual form, the anamorph, of many fungi looks one way and produces one kind of spore, while the sexual type, the teleomorph, of the very same fungus is totally different and produces an entirely different type of spore.
Put another way, the changing of the shape or form, biological function and reproductive methods (think sexual vs asexual) of the same fungus is usually driven by environmental cues and is what has resulted in the dual nature of fungal naming, simply because scientists until recent times saw them, naturally since the two forms didn't look anything like one another, as different fungi.
So still for many fungi the asexual stage and the sexual stage have different names, although the fungus is the same one. For the field practitioner, a lot of this doesn't make a huge difference, since most of the fungi we deal with and see out in the field like Botrytis gray mold, powdery mildew and anthracnose are in the anamorph stage, although it is worth noting that they do have a teleomorphic stage as well - Botrytis has Botryotinia fuckeliana (see photo below, it has not yet found in California, although every once in a there are rumors), Colletotrichum which causes anthracnose has Glomerella, and Zythia is the anamorph of Gnomonia. Powdery mildew, Podosphaera aphanis, of strawberry and raspberry, has made the transition to one name only for both the asexual and the sexual stage.
Speaking of Podosphaera aphanis, you might see it having another name, syn, Sphaerotheca macularis. It is a different story from the above. Sphaerotheca macularis is the former name of Podosphaera aphanis. You might see it used in some older literature. The name change was due to new genetic tools used for taxonomy. This blog post explains it in more detail (https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=4260).
What has been bringing the story of dual nomenclature nearer to a close - and yes there is plenty of controversy in between - is the use of the use of genetic analysis which allows for the close view of to confirm that these to our human eye differently formed versions of the same fungus are indeed the same.
- Author: Mark P Bolda
- Author: Mohammad Aghaee
Close readers of this blog will know that last year Mark noted toward the end of the season a very unusual looking insect in two of his strawberry research plots, which UCCE Entomologist on the Central Coast at the time Kirsten Pearson identified as the “spiny assassin bug”, an insect in the family Reduviidae of the order Hemiptera which includes insects very familiar to us like lygus bugs, minute pirate bugs, damsel bugs and big-eyed bugs.
These are not a common insect to find, and according to the literature are mostly found in meadows and weedy fields. At the time, Kirsten pointed out that these bugs being so few in number and generalist predators, meaning in strawberry along with lygus bugs they likely prey on all the above-named insects as well as ants and spiders.
Prey are killed by injection of saliva through their three segmented proboscis, and subsequently the internal organs of the prey is digested “pre-orally” so that the assassin bug can ingest it. This is fairly similar to the digestion method of lygus bug, which consumes plant matter much in the same way.
We can share a little bit about the biology of the assassin bugs. The eggs are deposited singly or in groups and are possibly covered by a glutenous substance by the female. Our reading of the literature indicates that there are not many eggs laid per individual bug, and there is only one generation of them in a single year.
On the whole, while an interesting and fierce looking predator in strawberry, given the information we have here, it seems doubtful given their low numbers that these assassin bugs could become a beneficial of much consequence in a program of prey management in strawberry. However, it is worth emphasizing as Kirsten did when we first starting finding them, that their presence does imply a level of healthy biodiversity in the field.
- Author: Mark P Bolda
In case you haven't heard or been outside lately, it's been real warm in the Watsonville-Salinas area the last few days. A lot of effects, like sunburn and softness of the fruit, have been pretty common but I also spied the damage on raspberry leaves depicted below in photos 1 & 2 below at a mite trial I was spraying this morning.
The damage is happening on some recently matured leaves of emerging primocanes (vegetative non-fruiting canes) and looks to be coming from the plant not quite keeping up with the water needs of those leaves and subsequently they burn and curl up.
What is notable and worth sharing however is that the negative effects depend on whether the plant is outside or inside of the tunnels that cover the large majority of our raspberry and blackberry culture on the Central Coast. All the burning and leave decline I observed was outside of the tunnels and none was seen on the inside (photos 3 & 4). Maybe this is not so surprising because of the reduction in the intensity of the Sun's rays by the tunnel's plastic makes it unusual to find sunburned fruit there and we must be seeing a similar situation now for the leaves.
Also recognize that the plastic on these tunnels isn't always super clean and could be reducing light penetration even more! The plastic is often used for three years or longer, and accumulates a lot of dirt, as you can see in photo 5. But perhaps this is not all a bad thing, one hypothesis for the consistent outperformance of raspberries in tunnels is that they are plants which originally thrived in the filtered light at the edge of forest clearings, so this enhanced reduction of light could, beyond preventing fruit and leaf burning during intense light and heat, be just right.
- Author: Mark P Bolda
- Plants per acreage: potentially up to 2,500 plants per ¼ acre
- Yield per plant: an estimated 250 flowers per plant every 3 months
- Approximately 600 fresh flowers = 1 pound
- Harvest method: Hand-picked individual flower tops (on approximately half-inch stem), or because of the growth pattern in which the flowers are on a stem above the foliage, mechanical harvesting might be possible
- Handling and shipping: Because we crush and macerate the flowers in high-proof alcohol to extract flavor, they do not require delicate handling such as with flowers used decoratively. Shipping can be done by vacuum bagging, boxing, and sending overnight via FedEx or UPS to Colorado.
Bob Tews
Tews Pro Services LLC
C 303 808-4072
- Author: Mohammad Amir Aghaee
- Author: Mark P Bolda
With the recent Section 18 permit to use Sefina insecticide for control of lygus bugs in strawberry, a number of growers and PCA's have approached both of us concerning the mode of action of Sefina, of which the active ingredient is afidopyropen.
From the paper included below we find that the mode of action is as follows:
"A recent study revealed that afidopyropen modulates the transient receptor potential vanilloid (TRPV) channels in insect chordotonal organs. Chordotonal organs, which are unique to insects and crustaceans, are mechano-sensors, which are located in the joints of body segments and provide information about relative rotation of body parts. Hyperactivation and eventual silencing of TRPV channels by afidopyropen perturbs function of chordotonal organs and leads to loss of coordination, which, in turn results in inability to feed, desiccation and eventual death"
Put another way, the mode of action is basically similar to an inner ear infection or what one can experience from an excess of alcohol consumption, in that the affected insect has a loss of coordination and balance. That makes them starve to death because they can't really attack the fruit again or makes them susceptible to predation.
It is valuable to point out that Sefina (afidopyropen) does have translaminar efficacy in the plant, but it does take time as you see with aphids in the paper. It is interesting to note that there is no downward movement of the chemical in the plant, they observed upward movement.
Horikoshi et al. 2022 afidopyropen
