Citrus Greening Disease

[grollies]

Or HLB affects us all here in Thailand.

 

Some interesting research has come out from GM Watch offering alternative reasons for the cause and treatment of the disease.

 

I'm specifically directing this post at @drtreelove as he is a big proponent of this.

 

Comment please Don.

 

https://gmwatch.org/en/news/latest-news/18803-expert-says-there-s-a-cure-for-citrus-greening-so-why-is-it-being-ignored

[notagain]

Read This

HLB_FarmerGuide.pdf

[drtreelove]

Thanks for that. I support this concept.  I was contacted by a forum member from Malaysia who has just completed 15 years of field work in China along the same lines, and they came to similar conclusions and have developed a similar successful program.

 

The ag world is slowly but surely waking up to the fundamental truth, that soil health is the foundation of plant health. And rejecting the falsehood of the powerful chemical fertilzer industry that since the second world war has funded and dominated university soil science.  Old information is being revived and noticed, particularly the work of Dr William Albrecht, and being carried into mainstream ag practices now by modern proponents of high nutrient density growing, like Neal Kinsey, the awesome worldwide work of Australian Graeme Sait (Nutrition Rules, Nutrition Matters), Steve Solomon (The Intelligent Gardener), who took much of his material from my soils guru (thanks to Rice 555 who tipped me to his work and book on this forum about 10 years ago), Michael Astera (The Ideal Soil, A Handbook for the New Agriculture). I used his mineral balancing system for my customers and my own garden and was seeing good results, so I went all-in on trusting his position that with balanced mineralization along with building organic matter content and active beneficial soil biology, that plant resistance to pests and diseases would be enhanced and so much pesticide use, including botanicals, would not be needed.  It worked in my own garden and for my customers. 

 

i grew up in Arizona with a father who was a Univerity of California educated horticulturist.  Apart from his work as a public parks planner, he managed citrus orchards. As a kid I hung out and played in the groves, so I inherited knowledge of the management practices as I grew into a tree care specialist myself.  The orange and grapefruit trees were planted on well placed centers that allowed a full foliar canopy all the way to the ground, this shaded the soil surface and preserved soil moisture. Along with letting the leaf litter remain as mulch, it also suppressed weed growth. 

 

They deep flood-irrigated every 10 days with up to 10 inches of water column, high burms that held the irrigation water as it percolated deep into the soil profile.  They fertilized with steer manure from the big feedlots outside of Phoenix, then lightly disced in between the trees but never under the driplines, and i never saw them spray pesticides or herbicides. But they did harvest bumper crops of big sweet fruit from the full foliar canopies of the healthiest citrus I've ever seen.

 

I started my weekend pruning career at 12 years old on citrus trees, just pruning out dead wood and light thinning. I will never forget the irrigation. - For a kid in the hot summer desert sun, 10 inches of water was heaven, we skim-boarded and splashed around and had a great time, then rested under the private spaces and cool micro-climate of the citrus canopies. All this taught me alot about tree care before i ever knew I would make a life of it.  Drip irrigation? Intense tillage and herbicides and chemical ferts? Give me a break, no wonder the trees are susceptible and sick!

[drtreelove]

The one thing I don't buy with some of this thinking, is the old "which comes first" scenario, in this case it's the bacterium or the psyllid. This article seems to indicate that the plant is weakened by the bacterial infection and then the infestation by the psyllid occurs after the fact. I don't think so.

 

I'm not a scientist, just an old tree worker since I was a kid, evolved over the years into tree doctor, trying to figure out the nitty gritty of what I'm working with. Unless we're talking about an occult phenomenon, or some science that I don't yet understand, for a bacterial disease to be present in plant tissues, it would have had to have a method of entry, a path of introduction; it doesn't just manifest out of nowhere. Spores can be blown in the wind and rain, honey bees can introduce through flowers (fireblight), wounding can open a path of entry, or sometimes spores can land on bark tissues and create lesions that progress into systemic infections (bacterial cankers).

 

From what I've read from University of Florida and U California, from China and other research, it's been pretty well established that the Asian citrus psyllid is the primary vector of the HLB bacteria. It's a sucking insect that feeds on infected plants and then flies and feeds on uninfected plants where it inserts mouth parts and fluids and through that path of entry introduces the bacterium into the new plant. As far as I know, no other path of entry has been established. Tell me if I'm wrong.

 

The the susceptibility of the plant to infestation as well as for the bacterium to thrive, is where I join in the notion that growing conditions, soil and water management are fundamental issues. Detrimental practices also come into play, like years of hard chemistry applications in the form of chemical pesticides and high NPK fertlizers that disrupt soil health and the processes of nutrient assimilation.

 

It takes time and money to rebuild soil health after detrimental practices are discontinued. From my experience, with the "high nutrient density" approach (Albrecht school), with soil testing, prescribed mineral and biological amendments, building soil organic matter, mulching and intellilgent water management, some positive results will be seen right away, but it really starts to kick in with best results in about two years. That's when you start to see a reall drop off in pest and disease incidence, due to building of plant resistance.

 

If you are committed to a comprehensive organic program, no hard chemistry pesticides or fertilizers, intelligent soil and water management and IPM, during that two year period of time, it is especially important to keep up with a preventive spray program to deter the feeding by the disease vector, the ACP. Unfortunately, soft chemistry botanical insect pest repellents don't have a long residual effectiveness.  This means spraying neem or another botanical will have to be done every two weeks, or every week during high risk periods of the pest life cycle.  But it makes an organic program time consuming and expensive.

 

Azadirachtin (neem extract) concentrates are available, and are effective as a repellent, feeding and reproductive disruptor, but they are not cheap, especially with two week interval applications. Then there is wood vinegar and some other botanicals available, with which i don't have much experience. Aromatic oils, rosemary, clove, lemon grass, etc, some which you can make yourself, may be effective. They would be appropriate for citrus because the residual oils and odors would not be as much of an issue as it is with produce or thin skinned fruits that would have to be washed.

 

In my opinion, the spraying or injection of anti-biotics is unnecessary for HLB, unless it is ever proved that the bacterium enter through the flowers or by any other path than the psyllid feeding.  If you can keep the psyllids off the plants and from feeding, then there will be no bacteria in or on the plant to make anti-biotics an appropriate method of control.

 

This approach that I've suggested is concerned with prevention, for plants not yet infected. Pro-active vs reactive. The article that Grollies presented was oriented to curing active infections and declining/dying plants. Thats a tall order and something I have not been involved with.  But I like their approach of stopping detrimental practices and building soil health as a primary concerns for rebuilding plant health.  A proprietary curative formula? I guess everybody has to have something to sell in order to make ends meet.   

 

 

Edited March 15, 2019 by drtreelove

[drtreelove]

On ‎3‎/‎13‎/‎2019 at 7:53 AM, notagain said:

Read This

HLB_FarmerGuide.pdf 2.44 MB · 1 download

That's an amazing paper. thanks. 

 

I was out of touch and didn't know about the biological controls that have been explored. I'm not sure this could be achieved without a big gov backed program.  Unless its a very large orchard or community cooperative, biological control agents can get wiped out by overspray from a neighboring farm. 

 

I am pesimistic about practicality of some of the excellent program components and availability for Thailand.  Most of the sophisticated new biopesticide materials are not available here.  And those that are may not get enough percentage of control to satisfy local growers.

I like this:

-The important takeaway message from these studies and

publications is that:

-Insecticides approved for organic production use can

work almost as well as standard synthetic insecticides

but provide control for a shorter period.

-OMRI approved insecticides should be applied in

rotation and diligently in response to insect scouting

and sampling counts that meet action thresholds;

this could mean every 2 weeks.

-OMRI approved horticultural oils not only provided

strong control (80% adult mortality in some studies)

when used alone but can increase adult ACP mortality

to 97% when combined with other products such

as M-Pede or Grandevo.

(M-Pede is a commercial brand of insecticidal soap.)

Combine with horticultural oil is something I didn't mention before but I've used this tank mix for other pest issues with great success.

This paper indicates that insecticide and oil mix has longer residual than botanicals or soap alone. And this combo may be the most affordable. 97%, can't touch that with anything else.

 

[notagain]

And therein lies the problem, until the thai gov. abolishes the FBA allowing foreigners to farm and share knowledge and exp. with the farmers nothing will change. Also until they get rid of the ridiculous import duties we will never be able to import modern products or technology to modernize agriculture to make it profitable and grow healthier food. I went to horti-asia thailand a couple of  years ago and they had basically nothing availible except outdated/useless junk. The few things I did see I was interested in of course no distributor in thailand because of the import duties the companies couldn't make a profit bring it in.

[grollies]

1 hour ago, notagain said:

And therein lies the problem, until the thai gov. abolishes the FBA allowing foreigners to farm and share knowledge and exp. with the farmers nothing will change. Also until they get rid of the ridiculous import duties we will never be able to import modern products or technology to modernize agriculture to make it profitable and grow healthier food. I went to horti-asia thailand a couple of  years ago and they had basically nothing availible except outdated/useless junk. The few things I did see I was interested in of course no distributor in thailand because of the import duties the companies couldn't make a profit bring it in.

I'm with you 100% with that analysis. There are a tiny minority of Thai horticulturalists who grow organically - my friend down the road is a case in point. I've just got back from his place this morning and it depresses me how good his place is. Sensible water management, no chemical NPK fertilzer, lots of organic manure, his wife does mushrooms and the mushroom litter goes on the raised beds. He has everything under blue netting to keep pests out.

 

As for education of Thai farmers it has to come from the Kings Projects. Info on the net is 95% English language so not available to the average Thai farmer. In general though changing a farmer's mind here would be nigh-on impossible unless it came from another Thai.

 

Regarding importing equipment another friend asked me to import a piece of kit once...For him to copy and manufacture here.

 

 

[notagain]

I used to work at a Rajabaht college and knew the ag dept head who spoke english well. We talked about how bad the farm practices were here and he told me every month they would have a get together (free food and drinks of course) and invite all the local farmers in to try to get them to quit burning etc. teach them soil remediation etc. He said it was all just a waste of time as they would just go back home and burn everything.

[drtreelove]

On ‎3‎/‎13‎/‎2019 at 7:53 AM, notagain said:

Read This

HLB_FarmerGuide.pdf 2.44 MB · 2 downloads

Thanks again Notagain, and Grollies for the OP.  I thoroughly read this paper again today.  It's a Masterpiece, in my opinion. The beauty of it is in the comprehensive consideration of so many aspects of the disease, the insect vector, the various control options including cultural/growing condtions, biocontrols, and OMRI listed biopesticides. The authors are aware of some of the most recent biopesticide developments, and also include discussion of biostimulants, humic substances, microbial inoculants, seaweed extracts, microntrients, nanoparticles (? whew!),  impacts from environmental stress, and development of HLB resistant varieties.  This paper could/should be a guideline for how to comprehensively view modern organic land care and crop management, not only HLB.

 

Here's my favorite, the master statement from the conclusion:

 

"It is paramount that a grower applies many control prac-tices simultaneously to get the most effect from each. IPM acts synergistically; the results of the combined efforts will be better than the sum of each part added individually"

 

https://www.organic-center.org/wp-content/uploads/2019/01/HLB_FarmerGuide.pdf

 

And did you see this page:  https://www.organic-center.org/who-we-are/meet-our-scientists/

 

 

 

[notagain]

I must admit to not being in the past a big organic fan but with the recent technological advances in biological controls and other science/tech being applied to growing I will be using them more. I read most of the new research on horticulture and with the explosive growth of hydro and greenhouse production around the world I see quite a sea of change when it comes to horticulture which is nice. I will be leaving thailand soon after 10 years here back home (not to insult thailand but ive had enough) to some acreage I own there to start a small scale market garden incorporating greenhouse/hydro and soil crops for local markets sales and look forward to being able to buy and use all of this great new tech.

[Grafting Ken]

Hi.. I'll go back to grollies first post... first of all are you sure it's citrus greening? Most citrus here is grafted onto pomelo and is not compatible with most citrus trees, also found that layered lemons and other citrus don't do too well... I'm putting trees onto Troyer, Volka and hoping to try some swingle citrumello soon... the difference on troyer compared to pomelo is huge. Probably because it's a recommended rootstock... I'll update on the others.
Sprays... I spray with a molasses and em based mix adding neem and seaweed extract after activating the em for just 24 hours.... been using this spray method for a while and found it very effective...
Once again lime lemon or orange on pomelo... forget it same as layered citrus in Thailand.


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