Islands Business - Agriculture: MILE-A-MINUTE A CONCERN TO FARMERS

Authorities work on controlling weed

Dionisia Tabureguci
Mile-a-minute creeps the countryside in most countries in the Pacific like a silent marauder and the truth in the agricultural sense is that it is a kind of a silent thief.

Gotcha... Butterfly larvae at work on a mile-a-minute leaf. Photo by Secretariat of the Pacific Community.

A thief of nutrients, sunlight and space necessary for the well-being of crops and vegetables grown for human consumption.

Although to the typical Pacific medicine woman, the mile-a-minute plant is essential for stemming the flow of blood from fresh wounds and is therefore an important natural medicine that should be readily available, the occurrence of the plant in some Pacific Islands countries (PICs) is increasingly becoming a concern to agricultural authorities.

In previous bio-security and plant protection workshops, mile-a-minute had been regularly named by agriculturalists from the islands as among the top 10 most damaging weeds in their countries.

Being a perennial creeper, mile-a-minute has been known to spread very fast creating thickets that in no time block out the necessary sunlight from surrounding vegetation.

Its nature as a creeper would see it quickly take over a wide area in a short while and if not controlled, would diminish the viability of plantations and home-gardens in its path.

Where traditionally the semi-subsistence farming communities have resorted to clearing out the weed manually or with the sporadic use of chemicals, control of mile-a-minute is considered a little more difficult when it is found in bigger plantations.

While this is so, little has been documented on the real economic cost of this weed to regional crop husbandry and agricultural industry.

However, agriculturalists familiar with the Pacific region believe that if quantified, the economic costs can be very high if one looks at it in terms of diminished yield and crop damage where uncontrolled mile-a-minute population suffocates crop plants.

In a first of its kind in the Pacific region, agriculturalists are bringing in a type of rust fungus to help control the population of mile-a-minute or Mikania micrantha, as it is scientifically known.

“Using fungus as a biological control for weeds is still a new concept in the Pacific and indeed in the world,” said Warea Orapa.

Orapa is the coordinator at the Weed Management and Plant Protection Service of the Secretariat of the Pacific Community (SPC).

SPC is involved with ACIAR (Australian Centre for International Agricultural Research) in a joint project to work on a biological control for mile a minute in Fiji and Papua New Guinea, a project that started early 2005.

“The use of fungus as bio-agent in the control of mile-a-minute had been tested by CABI (Commonwealth Agriculture Bureau International) in the United Kingdom and the fungus was released in the field in China and India where the weed is a big problem.

“We are benefiting from that experiment and research,” Orapa added.

The project is in fact exploring the possibility of using two bio-agents: a fungus and a butterfly. At the CABI test, according to Orapa, three rust fungi and two types of butterflies were tested for field release in China and India, where the occurrence of mile-a-minute is more serious.

The SPC/ACIAR team is working on the use of the two butterflies and one the rust fungus. The two butterflies (Actinote anteas and Actinote thyla pyrrha) are being reared at Koronivia Research Station while the rust fungus, scientifically known as Puccinia spegazzini, is being reared in the United Kingdom and will only be brought over for release first in Fiji when it has passed the safety test.

It is the use of the fungus that is of greater interest because it can spread diseases and for this reason can be more risky.

Bio-controls have traditionally been in the form of other animals or plants.

The Puccinia spegazzini spreads a condition known as rust, a type of copper-coloured residue after it has sucked the saps of the leaves.

SPC and ACIAR agriculturalists suspect that the type of mile-a-minute found in the Pacific islands was originally from eastern Ecuador because out of the three original strains of fungus tested, the Puccinia spegazzini, itself a native of east Ecuador, was the most virulent or damaging to the mile-a-minute of Fiji and Papua New Guinea.

It is for this reason that the Puccinia spegazzini has been chosen for the Pacific project.

While the SPC/ACIAR project has yet to reach the release stage of these bio-agents, Orapa said the safety of the fungus can be gauged from India’s test on over 200 plants in the last five years.

“India has ascertained that the fungus is safe. On our part, we have tested only nine plants that were not tested by India. As for the butterflies, we brought them in October and we hope to begin testing them soon against 33 plants.

It is the larvae of the butterflies that feed on the mile-a-minute so we are trying to get the full life-cycles before we begin testing them on the plants. The complete test will take about six to 12 months after which the butterflies may be released in the field. The fungus, said Orapa, has yet to arrive and would be more complex to administer. One of the people involved with the project will be going to England soon to learn how to rear the fungus.