- (Public Value) UCANR: Promoting economic prosperity in California
Just When You Thought You Could Take the Week Off from Webinars
Here's a two-day conference on Dragon Fruit
September 22 and 23, 2020 (you have an option of viewing it live or later recorded).
Note Taiwan is 15 hours ahead of California.
To register for this conference follow the link: FREE registration.
Please use the following link for the agenda
Besides the presentations on export there will be presentations on:
- Good agricultural practices
- Nutritional and functional traits of dragon fruit
- From production to consumption-the missing links
- Value-added programs
In addition: There is a lot of information on dragon fruit production through the
CRB Announces its
The Citrus Research Board (CRB) in coordination with the University of California Statewide Integrated Pest Management Program (UC IPM) is rolling out a new CRB Webinar Series, geared toward citrus growers and industry professionals.
Make sure you mark your calendars for the rest of the talks in the series.
For more information, please contact
Petr Kosina, with UC IPM, at email@example.com
So Sphaeropsis tumefaciens causes galls, but it's also been noted to cause witches broom in citrus, as well. Thjs type of broom formation is a wild, though compact growth. It's a dense mass of shoot growth from a single point – a messy mass that even a witch would have a problem using to sweep up. This is a symptom of infection by certain fungi, like rust or mildew or a genetic mutation in the plant itself. If it's a stable genetic change that doesn't alter over time, it could be used in the horticultural trade to propagate dwarfing plants. That might be good in the case of citrus, meaning less pruning. There's already the ‘Flying Dragon' rootstock that causes dwarfing, but it has some problems, like being really slow growing.
Anyway, another cause of undisciplined broom growth is phytoplasma infection. These are bacteria-like organisms that were only discovered in the 1960s and cannot be cultured. This makes it hard to work with them. They can cause debilitating weaknesses in plants besides the broom growth. To complicate the culturing issue, it has a conspirator, which needs to be understood, as well. The phytoplasma is spread by an insect, the same way the Liberibacter bacteria is spread by Asian Citrus Psyllid, causing HLB. So it's necessary to know the biologies of two actors, plus how they interact. The problem of HLB, again.
In India and Iran, there is a crippling disease of lime caused by a phytoplasma that is spread by leafhoppers. You need the specific leafhopper to spread the phytoplasma to spread the disease. No leafhopper and it's unlikely that even if the phytoplasma were here, that it would get spread.
The internet is democratizing. It spreads all kinds of information equally to everyone. So an image comes across my computer, asking if I think the wild growth on the ‘Pixie' mandarin is this WBDL (Witches' Broom Disease of Lime). I don't think so, but you never know what is going to pop up. I was thinking it's probably Sphaeropsis on a new track, and whatever, need to check it out.
And there it is. The wild growth. It fills about a third of the canopy of the little tree.
There's even this flattened stem. Truly weird.
But something does not look right. Is it the phytoplasma causing other types of growth? The leaves don't look right. Citrus leaves have a central vein, with lateral veins. The leaves on the affected part of the tree only have a single mid-vein.
This is not a citrus growth deformity. This is some other plant. Following the stem of the deformed branch to the base of the trunk, there's the “sucker”. And it doesn't look like citrus bark.
This is not even a citrus plant. At some point, a myoporum seedling started growing there. The leaves are similar enough to citrus, that the grower thought it was a citrus branch than had become infected. Well, the myoporum did become ‘infected'. With what, I'm not sure. It could easily have been Sphaeropsis since it is in the Ojai area. Anyway, “when it doubt, cut it out”.
And here is the neat little tree, a third of it gone now and the interior exposed to sun so that it will need to be whitewashed to protect it from sun damage. But, it's not WBDL. This time. It's important to keep looking for what nature and hitchhikers can bring us. It could be a whole lot more serious.
Convolvulus can be an ornamental plant. There is a reason it is called MORNING Glory. It's why people plant it. It's commonly sold in nurseries. There's a large purple flowered variety that is growing throughout my Ventura city neighborhood. It's quite charming highlighting the orange fruit high in the canopies of citrus and along backyard fences. There are also pink stripped varieties. They also seem to grow well, and when you decide it's time that they had taken over too much of the garden, it's really hard to get rid of them The seeds are everywhere and they lie dormant, ready to emerge to recolonize that orange tree you had just cleaned out.
Listen to Weedologist Lynn Sosnoskie's advise on how to deal with this beautiful menace in the orchards. This podcast is prepared by Phoebe Gordon of UC's "Growing the Valley".
- Author: Rebecca Ozeran
A few months ago, I was asked about the toxicity of various plants in a horse pasture after the death of a miniature horse using that pasture. While many of the identified plants were chemically harmless (such as filaree [Erodium spp] and some native clovers), the pasture did have fiddleneck (Amsinckia spp) and popcorn flower (Plagiobothrys spp), two native forbs with potentially toxic chemistry.
Popcorn flower (above) has small white flowers. Fiddleneck (below) has slightly larger yellow flowers. Both plants have similar overall shapes: slender flowering stems, relatively small leaves, and hairs on all parts except the flowers themselves.
Fiddleneck is a known alkaloid accumulator and popcorn flower is similarly suspected to accumulate alkaloids. There are no cases that I have found where popcorn flower was identified as a cause of toxicity, however. Most research on popcorn flower chemistry focuses on insect herbivores which like to eat plants with alkaloids, to protect themselves against predation (e.g. Hartmann et al. 2004) – but that's a topic for another blog!
Alkaloids are secondary organic compounds produced by many plants. Different types of alkaloids have different interactions with animal biology, some of which are benign or beneficial, and others which are harmful. Some alkaloids you may have heard of include morphine, nicotine, and quinine. Pyrrolidizine alkaloids, the type found in fiddleneck and popcorn flower, have harmful effects. Toxicity often occurs when animals eat feed or hay contaminated with fiddleneck seeds, and some cases have been documented from animals grazing the plant in a pasture. Fiddleneck alkaloids can cause liver disease and death of horses, cattle, and pigs, but sheep seem to be less vulnerable (Craig et al. 1985).
Both fiddleneck and popcorn flower may also accumulate nitrates. Nitrates convert into nitrites once the animal eats the plant. Nitrites then react with hemoglobin in the blood and make it unable to carry oxygen. This oxygen deficiency can cause death in a matter of hours depending on the concentration of nitrates in the animal's diet. Sheep, pigs, and horses seem more resistant to nitrate poisoning while cattle are most vulnerable (Tucker et al. 1961).
How to avoid livestock poisoning by fiddleneck and popcorn flower
The best way to prevent livestock poisoning by these forbs is to make sure there is plenty of good forage available. Livestock don't typically seek out fiddleneck or popcorn flower. Fiddleneck and popcorn flower have more stem than leaf, so they aren't very palatable, and they are densely covered in hairs that tend to discourage grazing. In a pasture with plenty of grasses and desirable forbs, then, animals will easily avoid these harmful plants.
The risk of poisoning arises when there is little else for the animals to eat. As a pasture that has been overgrazed or a pasture experiencing a drought therefore might have too few plants for the animals to be able to avoid popcorn flower and fiddleneck. When possible, having more than one pasture can help keep animals safe. Animals should be moved out of pastures where the only available plants may be toxic.
Body size is also a factor in many cases of toxicity. A fully grown 1,000-lb animal may be unaffected by a small amount of these toxins in their diet (such as this horse, pictured above, who ate a mouthful of grass plus a single fiddleneck plant right in front of me), while a young or small animal might become seriously ill after eating just a few plants. Whether an animal develops clinical signs of toxicity or poisoning depends on the concentration of toxin in the forage, the quantity of forage consumed, and the animal's size. However, any amount could be harmful and if you notice your animals are consuming toxic plants, please contact your veterinarian.
Can fiddleneck and popcorn flower be controlled?
You are not likely to eradicate them, but there are ways to control these plants if you are concerned about them.
Both fiddleneck and popcorn flower can be hand-pulled – gloves recommended to protect against the hairs – if present in small patches. On small acreages, mowing an infested pasture before the plants produce seeds in the spring can help reduce the population. Some herbicides can also help kill these plants; generally speaking, you will need to apply herbicides when the plants are young and small, to prevent seed production for the year. Contact your local UCCE office for more specifics if you want to consider chemical treatments.
Long-term, re-seeding bare patches in pastures and ensuring moderate grazing can also help outcompete these species. Because they have relatively small leaves, popcorn flower and fiddleneck rely on plenty of open space and sunshine to grow. As a result, they are less common in pastures that are densely populated by desirable forages that shade smaller plants.
For more on establishing a healthy pasture, even if you have dryland pastures or pastures with animals other than horses, the free guide here is a great place to start: Establishing and Managing Irrigated Pasture for Horses.
If you are concerned that your animals may have been exposed to toxic plants, contact your veterinarian. If you have concerns about plants in your pastures, feel free to contact your local UCCE office for assistance with plant ID.
Check out CalFlora to see the geographic distribution of these and many other plant species in California
Craig, A.M., L.L. Blythe, E.D. Lassen, and M.L. Slizeski. 1985. Resistance of sheep to pyrrolizidine alkaloids. Israel Journal of Veterinary Medicine 42:376-384.
Hartmann, T., C. Theuring, T. Beuerle, L. Ernst, M.S. Singer, and E.A. Bernays. 2004. Acquired and partially de novo synthesized pyrrolizidine alkaloids in two polyphagous arctiids and the alkaloid profiles of their larval food-plants. Journal of Chemical Ecology 30(2):229-254.
Tucker, J.M., D.R. Cordy, L.J. Berry, W.A. Harvey, and T.C. Fuller. 1961. Nitrate Poisoning in Livestock. California Agricultural Experiment Station. Circular 506, 12p.