Combating citrus diseases

Agriculture: To prevent the two major citrus diseases, fruit dropping and citrus greening, all citrus farmers will need to put in place modified solutions provided by the agriculture ministry.

The two diseases were identified as some of the many causes for the drop in mandarin production across the country this year.

Various methods and technologies were used to control the diseases but the diseases were found to be emerging again.

A team from the National Plant Protection Centre over the past four years carried out research in the two gewogs of Kilkorthang and Dunglagang in Tsirang.

To wind up the research and promote technologies to combat citrus diseases, a two-day training was organized yesterday in Tsirang.

Plant pathologist (Dr) Thinley explained that for fruit dropping, a citrus fruit fly which is a small red-eyed fly that eats the unripe fruit causes it to fall. To curb dropping, the research paper recommends proper collection of dropped fruits and dumping them in a pit to rot in isolation. Doing so is expected to reduce the fly population.

“Each year if citrus farmers continue doing so the fly population will reduce until a time when no fly will be seen in a citrus orchard,” he said. “However, it can’t be done by an individual farmer, it has to be a community approach.”

Such solutions will have an impact only if all farmers follow the solutions.

The agriculture extension officer of Rangthaling gewog, Sonam Dorji, said that it is important that all farmers have a common understanding. Unless the whole community cooperates to implement the technology in curing citrus diseases, there will be no impact, he said.

“Community cooperation is the key in minimizing citrus disease,” he added. “It may not totally eradicate the disease but some changes are definitely expected.”

Some farmers are already burying dropped fruits but the impact has been limited because not all farmers have been following the practice. As some were not burying the dropped fruits, the fruit fly was able to migrate to other orchards and spread the disease.

The agriculture extension officer of Semjong gewog, ML Bhattarai, said the technology was introduced a long time back but now the technologies have been modified. For instance, to trap the citrus fruit fly insecticide was sprayed on the entire tree in the past but now it is sprayed onto just a few branches, so that the whole tree is not harmed but the fly still hit.

“This will reduce fruit dropping, when there is no dropping the production would pick up,” he said. “If not the chances of fly migration from one orchard to another are high and the fly population will keep multiplying and spreading,” he added.

One of the farmers in Kilkorthang, MB Kafley, who used the improved solutions during the research period said he noticed an improvement in production. Until 2013, his 95-tree orchard provided him with Nu 30,000 annually because of less fruiting and poor quality fruit. But in 2014 and last year his earning doubled as a result of the improved solutions.

In 2014, he got an income of Nu 60,000 from his orchard and despite the drastic drop in production across the country, he got Nu 100,000, last year. “I can see good fruiting next year, its flowering well this time,” he said.

Prior to the research in 2012, a nationwide survey was carried out which found that the disease was common across the country. However experimentation with the new modified methods were carried out only in Tsirang, given cooperation of the farmers.

“If all citrus farmers strictly implement the technologies, citrus diseases could be controlled if not eradicated completely,” (Dr) Thinley said.

However, the findings of the research does not provide any solutions or answers for the drastic drop in mandarin production this year.

One of the reasons for the decline, (Dr) Thinley said, was lack of orchard management, such as fertilization, insufficient nutrients, irrigation, and improper pest control. Moreover, the citrus tree has alternate bearing habits, where the production is good one year and drops the next year.

The research project was funded by the Australian Centre for International Agriculture Research.

Nirmala Pokhrel, Tsirang

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