Marjorie StairMY SECOND job, after graduating from St Andrew High School in 1967 and before proceeding to UWI, St Augustine to study agriculture in October 1968, was that of being a Laboratory Technician/Assistant to an African Entomologist, Dr. Apeji. He was working with the Plant Protection Division of the then Ministry of Agriculture and Lands on possibly Jamaica's most economically important pest, the West Indian fruit fly.
The work involved investigating a number of biological control methods and, if memory serves me right, doing a survey of the pest population at the same time.
The West Indian fruit fly larvae are those worms that you find in mangoes, guavas and plums. The pest has severely limited our mango export trade. The pest has numerous hosts and is to be found in hog plums, guavas, otaheti apples, soursop, just to name a few. In 1968 the pest affected mainly common mangoes, Bombay, hog plums, guavas and was of little importance to some of the other mango varieties. It was definitely not a pest of the Julie and East Indian mangoes. Today the population has exploded with every possible host being infested.
Mr. Walter Van Whervin, another entomologist with the Plant Protection Division, did some work on the pest for some time. A CARDI entomologist also worked on this pest in some of the other Caribbean islands. If the critical research work has continued then I have not been aware of it.
Mango is possibly one of Jamaica's most important fruit crops. Those who were born before the explosion of the West Indian fruit fly will fondly remember Louise Bennet's poem about mango time. As children we would laugh about eating 'stringy' mangoes at night in order to pretend that the worms did not exist, now many people have mango trees of different varieties and can hardly find a fruit to eat during the mango season. Many pay dearly for the services of those who claim they can control the pest to no avail. No longer are we able to turn down our pots because it is mango time.
One of the problems with attempting to do any type of analysis of the agricultural sector is that the trading of so much of our domestic produce is lost in the informal economy, as there is little or no record of this trade. I discovered this when I was doing my work on ackees for my Masters degree. The market for ackee in the USA has now opened up, after almost thirty years of lobbying, and we are still unable to accurately make statements about the volume of ackee produced or the amount consumed locally. We are unable to state domestic consumption levels of bananas or sugarcane despite having up to date and detailed statistics on the export trade of these crops and the fact that the domestic trade is significant. The trading of mangoes, except for those exported, is also lost in the informal economy, as is the trading of most of our local fruits.
The prevalence of the West Indian fruit fly and our inability to control it must have contributed to the increasing rural poverty as most of its hosts are not only consumed as fresh fruit but some are used as raw material for our agro-industry? How can we effectively develop the agro-industrial sector in an attempt to address the problems of our increasing rural poverty and unemployment if we are unable to ensure adequate supplies of raw material? This either because of pests and disease problems or because we are unable to do reliable forecasts of the volume of the raw material to expect at any one time of the year.
Mark Brooks has raised the issue of 'sick soil', mentioned in a previous article. My 'sick soil' story also concerns mangoes. I operated a plant nursery between 1985 and 1997. The top selling plant from this nursery was consistently the Julie mango plant. Householders wanted it, villa operators and small hotels wanted it, farmers establishing mango orchards wanted it. There is no mystery to this. The Julie mango is the most popular mango not only in Jamaica but elsewhere; it is one of the nicest mangoes and the small size of the tree allows it to fit neatly in even the smallest of yards.
In the early years we routinely fumigated/sterilised the soil used for potting with methyl bromide. In the later years we experienced considerable difficulty in sourcing this product locally and started using unsterilised soil on those occasions that we were unable to get methyl bromide or an appropriate substitute. After some time we started experiencing problems in producing healthy Julie mango plants. We treated it as a nutritional problem at first, getting the required soil and leaf analyses done and, based on the results of these analyses, started adding regular doses of micronutrients to our fertiliser regime for all of the plants in the nursery and zinc to the mango plants. This helped in the short term but after awhile we started losing more and more Julie mango plants. The percentage take of Julie mango buds dropped from 97 per cent to 100 per cent to as low as 30 per cent and 40 per cent. Needless to say this was not encouraging, given that the Julie mango plant was our top seller from the nursery.
Knowledge
I consulted anyone or any source of possible knowledge that could address this problem. Eventually, after discussion with the Plant Protection Officers at Bodles Research Station, I took a sample of the plants to the Plant Protection Laboratory there. The results revealed a complex of soil fungi and anthracnose, a fungal disease on the plants themselves. They recommended restricting budding to the drier periods of the year and the application of soil fungicides. We followed this recommendation and added the routine application of soil fungicides to our pest and disease control regime. The loss of mango buds was reduced only marginally. Budded plants that survived did not thrive and remained very weak and looked unhealthy. A few of our customers also started complaining of losing some of the Julie mango plants, after planting, that had appeared quite healthy when they left the nursery. They also reported that those plants that survived looked weak and did not thrive. We tried every possible thing.
I had met Dave Hutton, Nematologist, whilst working with Dr Apeji at the Plant Protection Division in 1967/68, and had been in recent contact with him in the early 1990's while doing work on ackees at the Botany Department, UWI, for my Masters degree. I called him out of sheer frustration and he suggested that I take a specific number of plants to him so that he could run a little experiment with them. He did as promised. Two things stand out clearly from this experience. First, I remember him telling me that normally on doing soil extraction for the particular nematode species found in my Julie mango bags, three nematodes would be an indication of a very high nematode population. He extracted as much as 20 nematodes from some of my plant bags.
Drought or flood
Secondly, he showed me a picture of three tobacco plants, that I wish he could show to all of those Jamaican agricultural leaders that have been simply writing off our agricultural decline to drought or flood. The picture is a vivid demonstration of the meaning of 'sick soil'. One plant was in the middle and, if it had not been positioned beside the first picture, would have looked like a perfectly healthy tobacco plant. It was infested with a relatively high level of nematodes. The first picture was about twice the size of the middle picture, lush and green and free of pest and disease. The third picture was like one of my Julie mango plants, or a malnourished child. Not dead but barely surviving. The leaves were a dull green colour and the whole appearance of the plant was unhealthy. A complex of soil fungi and soil nematodes affected this plant, similar I suspect to the sort of disease complex that caused our breadfruit decline. The trading of breadfruit, by the way, is also lost in the informal economy - this very important staple food.
Dave Hutton had experimented with a number of different nematicides, applying them at different rates. The only one that successfully controlled the pest and caused the plants to recover and become healthy once more was Miral 5G. He recommended using steam to sterilise the soil before potting. Thanks to his willingness to assist in this way, we were able to continue to produce Julie mango plants until the nursery closed.
These are the lessons that we learnt as a result of our Julie Mango problem. Apparently healthy plants can be sick if, first of all, we have nothing better with which to compare it, and if we do not observe them closely and regularly so that we can notice any early changes in appearance or performance. Accurate records of input use, costs, yields and revenue are also of critical importance. I guess this applies to many other things other than plants. The importance of the regular application of micronutrients to plants in the nursery and the need to apply zinc to mango plants. The importance of regular analysis of both soil and leaf tissue to determine plant nutrient requirements and identify pest and disease problems, especially populations of soil fungi and nematodes. The significant influence of weather on the incidence of pest and disease and action to be taken, simply by monitoring the weather and restricting certain cultural practices to the most appropriate weather conditions, to reduce the incidence of pests and diseases. And there were others.
Experiences
The point of sharing these personal experiences with you in discussing the decline of Jamaica's agricultural sector is this. In the early 1990's when we started to experience the problem with the mango plants, I was a trained Agronomist with over 20 years experience in agriculture. I had worked as an agricultural researcher, been in charge of agricultural extension, worked as an Agricultural Extension Specialist and had been engaged in farming and the plant nursery operation. I had knowledge, experience and contacts. It was not enough.
Some of the information is not available locally. Some of the services, if available, are severely limited, costly, or are simply not available on a timely basis. There is no point, for example, of sending either diseased plants or soil samples to the lab if you are going to experience considerable delay in obtaining the results.
We like simple solutions to complex problems and quick answers to questions that require sustained long-term research effort. We cannot stop work on plant pest and diseases once we identify a successful product, especially when we are so dependent on the use of chemicals for control, because they build up tolerance and resistance and new races and strains will arise unexpectedly. Banana industry experts can tell you about the explosion of Black Sigatoka in dollar banana countries because of heavy dependence on a single 'miracle' chemical.
We cannot stop work on fertiliser use, macro or micro nutrients, as each day there is new information on the physiology of the plant and new and better plant varieties are being developed with peculiar needs. In the time of precision agriculture, we need precise and accurate information if we are ever to become not only competitive but also if we are to put ourselves in a position to feed our nation. If we do the work, we can manipulate our weather conditions instead of becoming helpless victims of its vagaries.
The farm remains one of history's most important inventions, as T.R. Reid tells us. Farming has brought some of its own problems, however, that must be addressed if farming activities are to be not only sustained but become more efficient. It is the Jamaican people, the leaders of the agricultural sector, and its opinion and political leaders who must decide if the food on our table will come from farms overseas or Jamaican farms. This has nothing to do with buying Jamaican or eating Jamaican. This has to do with implementing the correct paradigm, one that will make our agriculture competitive and profitable. It means going back to the basics.
Marjorie A. Stair is an agronomist and horticultural specialist who now lives and works in St. Vincent.
