fruit diseases

In, 2021 florida had its worst orange crops since world war ii that's because this insect is waging a war on the state's valuable citrus trees so this tree is infected with citrus greening it produces small misshapen fruit just see the difference this disease can be a tree killer the insect spreads a disease called hlb or citrus greening and it's infected nearly every citrus grove in the state less canopy you can see there's just less foliage on the tree you can see through the tree the oranges are still edible the real problem is that citrus greening has slashed florida's production by 78 it's cost the state nearly 8 billion and driven many growers out of the industry you should go back in your mind 15 years to what this place once was as a collection of varieties this was full of beautiful green trees we've had freezes hurricanes but citrus greening has definitely been the most challenging issue we've faced in my career this group of scientists is racing to find a cure armed with some unique weapons this is about the size that we're going to put on most new trees now the researchers have helped growers produce oranges on the infected trees but they haven't found a long-term solution yet we will have to lift with the infected trees and just make the most out of them so can they keep this disease at bay before it wipes out the state's orange industry we head to florida to find out larry's a fifth generation farmer in fort meade florida we've been growing citrus in my family since the 1850s when i first started in the industry citrus occupied over 900 000 acres in the state of florida in fact some years we had too much fruit and market prices were depressed just 15 years ago his family packed a million orange cartons a year mostly valencia oranges the big sweet juicy kind you planted a grove expecting that to last for multiple generations the first case of citrus screening was reported in china back in 1919 it quickly spread across the continent devastating citrus groves in india and saudi arabia as well no one knows exactly how the asian citrus psyllid made it to florida but in 1998 it showed up on an orange jasmine plant in a backyard in palm beach county and it quickly spread throughout the state on infected root stocks but it would take another seven years before florida's orange trees showed signs of greening it spreads throughout the state before you even know it's present and in 2005 larry found his first infected tree it was a real challenge and an eye-opening for us we knew what a threat it could be to our operation and we were fearful there were more infected trees that just had not been detected at first larry tried removing all the sick trees but the insect moved faster soon infecting too many to control when a psyllid munches on a citrus tree it leaves behind the bacteria that causes greening here in the vascular tissue the bacteria replicates and blocks this important highway for removing nutrients underground the root systems thin and die out above ground you notice the yellow pattern the dark green spots if you can see me through the canopy of this tree that means this tree is really really sick while the trees do keep burying oranges for a few years the fruit essentially never ripens you see it's small in size it remains green and when i cut this fruit you see an odd shape you can still eat the fruit it's just not as sweet [Music] the orange juice from this fruit uh has lower sugar content or bricks than normal fruit but there's nothing wrong with the juice it's awful and 40 of those oranges fall off the tree sooner than usual the bacteria is actually starving and kills the tree over time today researchers estimate 90 percent of all orange trees in the state have the bacteria no longer do you see citrus trees abundant in the landscape larry has kept his trees alive in producing for 15 years using a combination of horticultural techniques developed by scientists at the university of florida some of our work that is going on right now is finding ways to keep those trees that do have the disease still producing fruit that are usable you guys want to see what some solids look like yes all right so they're very small oh there's an escapee actually they're small they kind of jump around a little bit so we use this thing called a an aspirator or the more fun term we use with children is pooter we just suck them up it's basically a little vacuum in my hand here lauren deep and brock can study the psyllids movement to learn what might keep them off a citrus tree using the aspirator is actually a really efficient way to collect psyllids she's figured out a few things that detract psyllids first this pink clay it's sprayed on the trees to hide the leaves from the insect which uses light wavelengths to see one study showed the clay was more effective than insecticides the second thing lauren is researching is these eight foot wide sheets of plastic called reflective mulch the idea is that it should make it where the cylinder can't find the host plant it could be that it blinds them or causes a visual deterrent i see the work uh somewhat we do get psyllids we do get them but we do get them at a reduced rate a few years ago farmers discovered that putting plastic bags around baby trees could help them grow stronger before infection lauren's now studying how effective these individual protective covers or ipc's actually can be so this is ipc mesh and as you can see there's little holes in it you can see my hand very clearly wind sun rain it all gets through here the goal is to really keep that asian citrus psyllid off the tree and then if you look underneath this is our irrigation the baby trees will grow in the ipc's for two years so you can see the trees aren't perfect we're still going to have some stuff on them we do have some pest issues in here but they look really good compared to what's in the open field and this will actually give our trees a fighting chance once they're out in the environment and they could potentially get infected with sea last scientist tripty vashish thinks the key is in the soil we have been learning that the trees need these nutrients to fight infection the citrus trees because of this disease have very small roots or fewer roots so they are not very efficient in picking up the nutrients it's like a job of 10 people needs to be done by one person same with the roots she figured out that giving smaller doses of fertilizer and water more frequently helps the sick roots absorb nutrients better and it's similar like us at six small dough meals each day rather than three big meals are better same as with the fertilizer and irrigation smaller doses are better than big doses larry uses fertilizer custom designed for his trees he's also planting more young ones one of our strategies for dealing with greening is to plant the groves at higher densities we're planting 300 trees per acre compared to 140 to 150 trees per acre before we were dealing with the disease so if he knows all the trees will get infected with more planted hopefully some will survive growers have also tried releasing predator wasps and spraying insecticides while there's no silver bullet in combination these short-term solutions have sort of worked you can slow down the decline we've been battling citrus screening for 15 years and while the industry is not thriving we're definitely surviving but the problem is all these approaches tack on an extra 600 per acre onto production costs for growers our revenues are down by more than half on an individual growth basis growers are losing money and many couldn't swallow the losses by early 2022 half of florida's orange growers had left the industry so while he waits for a long-term solution larry's taking the hit so he can keep harvesting the same way his family always has workers quickly pick the oranges and drop them into bags once they've got a good batch pickers dump them into baskets in the grove workers then truck the oranges to the packing facility just down the road we have eight digital cameras that takes a picture of each piece of fruit as it travels through the packing line we use an electronic sorter to divide the crop by color if they're orange enough the fruit gets cleaned and hit with a layer of natural wax it preserves the fruit it extends its shelf life today because of hlb larry packs half as many boxes as he did 17 years ago if the oranges are a bit too green larry knows they'll be hard to sell on the fresh side so he sends them to get juiced at the florida's natural plant in lake wales larry owns the juicing plant along with other local growers as part of the company's cooperative about 90 of the fruit grown in the state goes to orange juice but just like growers the factory has been getting fewer oranges so less efficiency in the plant with a lower fruit volume the factory had to shut down one of its three processing lines nowadays sixty thousand boxes of oranges arrive at the plant from cooperative farms across central florida that's about 30 000 fewer than before hlb within 24 hours of harvesting the we juice the fruit this machine squeezes the juice out of every orange we pull out any seeds and we also collect the pulp where we can add that back to whatever degree we want to do that the juice gets pasteurized and then pumped into cartons but remember greening affects oranges natural sugar content so florida's natural has to blend infected oranges with sweeter ones from different regions or even seasons it still tastes like orange juice it's just not quite as sweet today the factory pumps out about a third less than pre-greening they need a home for their fruit where they can get maximum value that hopefully can sustain their operations until a solution to greening is found many scientists believe the long-term solution lies with re-engineering nature either genetically changing the bug itself or naturally breeding citrus trees ultimately a tree that's resistant or tolerant to the disease will be key that's the project fred gameter and his team are working on at the university of florida they're trying to breed for an hlb resistant orange variety meaning even if the disease shows up the tree won't get sick to do that he takes two different types of trees maybe one with yummy oranges and one that's resistant and essentially has the mate and their kid will hopefully still taste good but won't get hlb that's really the holy grail of citrus greening research but that's not easy finding a resistant orange is like looking for a genetic needle in a haystack it's extremely difficult to breed new oranges we know of some kinds of trees related to oranges that are resistant and we're trying to access the genetics of those resistant types by making crosses fred says it could take more than a decade so it's long term there's always an element of serendipity in this but armed with that miracle-resistant tree they could be better prepared to tackle future diseases it's a global interconnected world we live in people and plant diseases move about pretty freely and so there will be another problem another disease come along i believe science will continue to deliver new tools that will make growing citrus easier over time i look forward to those days i'm sure we'll have other challenges that we'll face in time but today citrus screening is here to stay