I mostly had Caribbean fruit fly in mind when I wrote that, since it also reproduces on mature (not just rotting) fruit. And Florida is constantly subjected to new introductions of other fruit fly species that haven’t yet established. Having a lot of neglected fruit trees with owners that aren’t paying attention to the fruit makes it harder for new infections to be eradicated.
3 Likes
Asian citrus psyllid (the carrier of citrus greening disease) does not seek flowers or fruit. It chews on leaves.
In temperate parts of California, a significant number of homeowners grow Curry Leaf (Bergera koenigii) – a member of the Citrus family and a host of asian citrus psyllid. The homeowners have unwittingly played a role in the widespread infestation of asian citrus psyllid in metropolitan areas.
2 Likes
Greening doesnt come from the fruit nor does it come from ACP. It comes from infected plants and is spread by ACP feeding on that infected wood and bringing it to healthy trees. Its similar to mosquitos with West Nile virus. They need to feed from a source and then they spread it when they feed on others.
ACP can host on many plants in the Rutaceae family, including our native wild limes (zanthoxylum fagara). Curry-leaf and Wild Limes however do not host greening. If there was no greening infected citrus, then the ACP would merely just be a nusiance bug.
3 Likes
But also if there WAS localized greening AND fewer adequate hosts it definitely would’ve been harder/taken much longer to spread, your point is well taken though
2 Likes
what citrus species or cultivars are more resistant?
Supposedly Sugar Belle and Australian finger lime among others
5 Likes
Regarding soil fertility and HLB
Here they hypothesis higher soil organic matter and microbial activity may have a preventative effect.
https://www.sciencedirect.com/science/article/pii/S294991942300016X
And here phosphors deficiencies are noted to increase susceptibility.
Also,
From Frontiers | Controlling Citrus Huanglongbing: Green Sustainable Development Route Is the Future
5 Likes
It comes from Asia “Asian Citrus Psyllid (ACP)”.
I understand that but i meant the bug surviving on the fruit being transported here.
Satsumas do not have any resistance, but they can be grown in areas with no HLB due to their cold hardiness.
Any citrus grown in Maryland will be safe from HLB unless previously infected. HLB has so far only reached as far north as coastal South Carolina. The insect that spreads it has reached a bit further north but not too Maryland.
But anyway, if HLB is on your mind, Sugarbelle is the most resistant commercial variety.
https://www.emcocal.com/sugar-belle-citrus/
A few other varieties might be as well, but research is still ongoing and most of them aren’t really available yet. US Sundragon is over that’s making the rounds currently.
There are also a number of HLB resistant or tolerant rootstocks, most of which have some trifoliate parentage as trifoliate tends to handle HLB well.
Some of the Australian species may also be good, but with the exception of Australian Desert Lime, none are at all cold hardy.
2 Likes
…but there are enormous differences in the degree of susceptibility, in the resistance to infection, and in tolerance of the disease.
2 Likes
Thats not impossible, but its unlikely. They feed and nest on the leaves, so they aren’t found in the fruit very often. The most likely theory was someone smuggling in plant matter from Brazil or Asia.
I will note that the bug predates greening in Florida by about 7 years and were more likely brought over in seperate instances.
4 Likes
@a_Vivaldi
The first paper is a study of a FL orchard by Colorado researchers.
The second paper is a review article by researchers in Guangzhou, China.
I agree that unhealthy trees are more susceptible. But in the face of high disease pressure, all trees are susceptible.
… according to promoters of the research. In the face of high disease pressure, the differences are moderate.
True. But the presence of Curry Leaf has contributed to the ubiquitous infestation of ACP in temperate metropolitan areas of CA – many of which are adjacent to large scale citrus farms.
Then you have traders/sellers of Citrus plants on Facebook etc. from FL and TX that ignore phytosanitary laws. Cuttings and plants from these individuals end up in CA municipalities, then turn out to be infected with greening disease, and because of the ACP presence the disease is rapidly spread to other non-infected citrus in the area.
1 Like
Correct, showing that the effect is not geographically limited.
The strength of the effect is still up for debate, that is true. I’d not expect to see good evidence, in either direction, from places with only a short history of HLB, such as California, where the disease has only been present for a little more than a decade.
I’m glad you are researching the topic. I recommend checking out recent papers from UC researchers, albeit many are behind pay walls.
This is false.
And numerous USDA trials.
It’s been known since 2009 that the response is different. Now, you can always debate is it’s a significant or moderate difference, but that’s just semantics.
1 Like
Truth
4 Likes
2012 was a little more than a decade ago. That’s a short history of HLB.
Florida has two decades of history with the disease.* And under far greater differences of climate, soil conditions, and geographic area. I trust two decades of data from a large state more than ten years of data limited to basically the suburbs of a single metro area.
*And China has a much, much longer history of it. Hence, among other reasons, why it makes sense to listen to what the folks in Guangzhou have to say.
2 Likes
That’s what they said about Zika, and then sprayed more chemicals to kill mosquitoes.
That’s what they say about flu and a lot of other “viral” diseases.
I had tiny seedlings dying of an infectious disease, so I added 2 8 watt LED flood lights because the window was on the west and slightly North in a forest and not letting much sunlight through, and they went from mostly dying to 95% survival of an “infectious” disease.