Imagine a world without orange juice – unthinkable, but it could happen. The cause: citrus greening. An entire industry is in danger as a result of this disease. Globally, millions of citrus plants have been culled, and there is no cure available. Together with growers, processors, and researchers, Bayer is working on holistic and sustainable solutions to combat the disease.
“If the greening continues, we do not know how this ends,” says Jim Snively, vice president of Southern Gardens, one of the top ten orange growers in the US state of Florida. He first detected the citrus disease Huanglongbing (HLB), as it is also called, in 2005. “We were the second commercial operation that was confronted with the disease,” recalls Snively.
Once a tree is infected, it does not recover and its fruits do not mature properly. They turn green and sour. Three to five years after being infected, the tree dies. The major orange producing areas have already been impacted by the disease. In Florida, nearly 100 percent of the plantations are infected. In China, nearly eight percent of citrus growing areas are affected. And in Brazil, one fifth of trees are showing symptoms.
As a result, the citrus industry is in danger: 8,300 full-time equivalent jobs were lost in Florida between 2006 and 2013, and related economic damage of 4.5 billion dollars occurred in the Sunshine State. Jim Snively and his team have had to cull nearly 700,000 trees.
Citrus greening is transmitted by a little insect known as the Asian citrus psyllid. It feeds on the leaves of orange trees, through which it spreads the bacterium Candidatus Liberibacter into the phloem. The infection blocks the phloem, which supplies the tree with nutrients. “The challenge is that the psyllids mature rapidly. In only 17 days, a grown-up insect has developed out of an egg. Eight to nine generations can develop per year,” explains Kai Wirtz, Global Manager Fruit at Bayer. If the conditions are good, even 30 generations are possible. One single nymph can lay 800 eggs during her lifetime.
Jim Snively, Vice President of Southern Gardens, Florida (USA)
The disease has been known for a long time. It was detected in China in the 1920s. From there it spread around the globe: in 1937, the first descriptions of citrus greening appeared in South Africa, and it was reported in Thailand in the 1960s. The spread of the disease has accelerated over the past decade. It was found in Brazil in 2004, and in Florida one year later. Last year, HLB was detected in Egypt. So far, the disease has not reached Europe. However, according to experts, it is only a matter of time as the vector was seen in Portugal and Spain in 2015 but was not carrying the bacteria.
An integrated approach to fighting citrus greening
“We need a solution as soon as possible as the entire supply of citrus is at stake,” says Wirtz. “We are committed to developing and providing sustainable solutions that enable growers to continue producing citrus.” Bayer is therefore pursuing a holistic approach – firstly, by offering an integrated portfolio consisting of chemical and biological crop protection products to control the disease and keep the plants healthy and robust. Secondly, Bayer has employees around the globe that keep up with the challenges faced by growers. These employees visit farmers on a regular basis to provide training, for instance in correct product use and the development of efficient spraying programs.
Research activities are another important aspect of developing new solutions. For example, Bayer supports the Citrus Research and Development Foundation (CRDF) in Florida. The organization has two main research areas. On the one hand, they target the vector and its reproduction. On the other hand, they are trying to breed trees with greater resistance. Citrus growers benefit from research findings in their daily work. “The results from the nutritional and crop protection studies help us keep the trees alive,” explains Snively. In addition, Snively hopes that the researchers will manage to breed a citrus species that will be resistant to citrus greening. At the moment, the newly bred plants are being tested in trial fields. According to CRDF, the first trees are expected to be ready for commercial use between 2019 and 2021.
Joining forces against the disease
Bayer has joined forces to fight citrus greening around the world. In Brazil, for instance, Bayer is collaborating with Fundecitrus, an association for citrus growers, with the aim of facilitating faster development of technologies intended to ensure sustainability in citrus farming. To improve the situation in China, Bayer is helping citrus farmers with its “Much More Citrus” campaign and funding research at the Chinese National Agro-Tech Extension and Service Center (NATESC). And in California, where so far only private citrus trees have been infected with citrus greening, Bayer is supporting the #CitrusMatters awareness campaign, which was initiated by the California Citrus Mutual association, to make homeowners aware of the disease and avoid uncontrolled spreading in private gardens.
Citrus greening has spread rapidly around the globe over the past ten years and is a serious threat to healthy eating habits. The price of orange juice has been rising due to less production. “Price is the number one reason why less juice is consumed,” says citrus grower Snively.
In fact, fighting citrus greening is a matter of importance for the entire food value chain. That is why the Bayer Food Chain Relation team is also working closely with its various partners to find a solution. “We’re collaborating with our partners on various citrus initiatives to secure yields and continue producing high-quality citrus in a sustainable manner,” comments Stephan Brunner, Global Key Relation Manager at Bayer. “For Bayer, a world without the sweet juice is unimaginable,” adds Kai Wirtz. “Therefore, we are committed to our mission: Science For A Better Life. Together with our partners we do everything to support the citrus industry and tame the yellow dragon.”