Sunday, November 6, 2011

Environment and Health: Pesticide-Free Vegetables

Dr Abe V Rotor and Ms Melly C Tenorio
Paaralang Bayan sa Himpapawid (School-on-Air)
738 DZRB AM, 8 to 9 evening class, Monday to Friday
Lesson for November 9, 2011

Squash flowers and saluyot (Corchorus olitorius)

I am writing this article in response to queries on how sure are we that the vegetables we are eating are safe from pesticides.

In general leafy vegetables (e.g. pechay) and fruit (tomato) vegetables receive more chemical spraying than do root (potato) and seed (mungo) vegetables, but this is not always true as we will see later.

As far as our problem on pesticide is concerned, I would rather classify vegetables into two: those that do not need spraying at all, and those which can not be raised economically without the protection of chemicals.

For the first category here is a list of 30 common vegetables in their common and scientific names. Farmers simply find them resistant against attacking insects, mites, nematodes, snails, fungi, including weeds, rodents and birds – or these vegetables are found in the wild, or in the open where they seasonally grow.

1. Malunggay (Morinda oleracea)
2. Saluyot (Corchorus olitorius)
3. Wild ampalaya (Momordica charantia)
4. Katuray (Sesbania grandiflora)
5. Batao (Dolichos lablab)
6. Patani (Phaseolus lunatus)
7. Sinkamas (Pachyrizus erosus)
8. Summer squash (Cucurbita maxima)
9. Native eggplant (round) - (Solanum melongena)
10. Native tomato (susong kalabaw) - (Lycopersicum esculentum)
11. Native sitao (short) – Vigna sesquipedalis
12.Seguidillas (Psophocarpus tetragonolobus)
13.Alugbati (Basella rubra)
14.Talinum (Talinum triangulare)
15.Native spinach (Amaranthus sp.)
16.Gulasiman (Portulaca oleracea)
17.Sweet potato (tops and root) – Ipomea batatas
18. Kangkong – Ipomea reptans
19. Pepper or Sili (labuyo) - (Capsicum frutescens)
20. Ginger (Zingiber officinale)
21. Rimas or breadfruit (Artocarpus altilis)
22. Sayote (Sechium edule)
23. Taro or gabi (Colocasia esculenta)
24. Kamoteng kahoy or cassava (Manihot esculenta)
25. Ubi (Dioscorea alata)
26. Tugui’ (Dioscora esculenta)
27. Kadios (Cajanus cajan)
28. Banana (Saba) – (Musa paradisiaca)
29. Sampaloc (Tamarindus indica)
30. Kamias (Averrhoa balimbi)

Most of these vegetables are native to our soil and climate and because of this, they have natural resistance to pest and diseases, which would otherwise attack, introduced varieties, especially those of foreign origin.
Gardening with kids, Lagro QC

Tinkering with the genes of indigenous species erodes natural resistance. Our native rice varieties for example, are resistant to pest, drought, flood, can compete with weeds, do not need much care, although they are not top producers. Genetically “improved” rice varieties became pampered with fertilizers; water, planting distance, thorough soil cultivation, and most specially spraying with insecticides and fungicides. They are likened to our present breeds of animals. Our poultry today can no longer thrive in the open, whereas our native fowls are “self-supporting”.

This is true with many vegetables. That is why commercial vegetables throughout their life cycle are provided with a “chemical blanket” to protect them from the onslaught of pests and diseases, many of them became destructive as a result of induced mutation. Indiscriminate chemical spraying has been found to build biological specialization so that certain insects and pathogens, which survive, carry on to the next generations the acquired resistance.

It means therefore the need for more spraying, more frequent and higher dosage, above all - more poisonous chemicals. And this is what is happening today with many vegetables in the market. The pesticide industry greatly benefits from this situation.

Pesticides are believed to be the most common source of poison that causes ailments of the liver and kidney. They affect our nervous system and impair our senses and nerves. They have long been tagged as a major cause of cancer, diabetes, allergy and other physiologic disorder. Because most of the pesticides today are synthetic, our body cannot readily degrade and excrete them. Instead they tend to accumulate until a threshold level is reached that lead to many health problems.

Let us look at the second category of vegetables: those which are grown successfully only with the aid of pesticides. Without pesticides, they cannot survive the attack off pests and diseases.

The most sprayed vegetables are the crucifers – cabbage, cauliflower, lettuce, mustard, pechay, wonbok, and the like. The pesticides used on them are the most potent brands, leaving no chance to caterpillars ensconced in deep holes, mites in the roots, and aphids in leaf axils. The poison must be absorbed and distributed throughout the plant so that any insect that feeds on the sap is sure to get the poison and die. This is why such poisons are called systemic.

Poisons of this kind are also used on cucurbits, mainly melons and watermelon and cucumber, patola and ampalaya. The number one enemy is the fruit fly (Dacus cucurbitae), which lays eggs on the young fruits. Mango growers also use systemic poison to protect the fruits from another species of fruitfly, Dacus dorsalis. Mango importing countries like Australia, Japan and the US impose strict regulations against fruit flies which also attack other fruits and vegetables like oranges and bananas.

There are vegetables that may have been sprayed long before they are harvested such as peanut (Arachis hypogea) and mungo (Phaseolus radiatus). Rice and corn are relatively safe from the pesticides sprayed on them during their growing period. It is the protective spraying before and during storage that must be strictly regulated.

What should we do with vegetables under the second category – those that are raised with chemical spraying as a prescribed horticultural practice? Here are some tips of getting the least effect of the pesticide used.

1. Avoid the organophospates. Get advice from the Fertilizer and Pesticide Authority, or from your agriculturist. Organophosphates are the most poisonous of all pesticides. Examples are parathion, azinphos, bromophos, demethon, diazinon, EPN, DDVP, TEEP, thiomethon. There are 70 organophosphates packed and marketed under different brand names in the FPA list.

2. Carbamates have lower lethal dosage and are therefore comparatively less toxic to human and animals. Examples are aldicarb, benomyl, carbaryl, carbufuran, carboxin, methomyl, cartap, thiobencarb. FPA listed more than 20 carbamates, which carry different brand names in the market.

3. Intermediate in toxicity between the two groups - organophosphates and carbamates – are the organochlorines or chlorinated hydrocarbons such as endusulfan. pertane, heptachlor, BHC toxaphene. Because the residual toxicity is not only stay long but persists in the organism it is carried through the food chain. Many of these organochlorines are banned. This is particularly true with DDT and Chlordane. Under FPA regulation the presence of these in the market is considered illegal.

4. Herbicides belong to two groups: chlorophenoxy compounds and nitro and chlorophenols. One big disadvantage of herbicides is their destructive effects to living things and the environment. But when it comes to toxicity, gram for gram, rodenticides or rat poisons are the most dangerous. Keep them away from humans and animals. Dispose used baits and containers properly, particularly the acute rodenticides (e.g. zinc phosphide and sodium cyanide). Note: these are highly regulated by FPA

5. Remember, spraying with chemicals is an ultimate recourse in pest control. Pest control must be integrated with good farming. That is why the government is pursuing Integrated Pest Management (IPM). Successful IPM models in other countries have drastically reduced the use of chemical pesticides. Follow the threshold level formula that means, spray your field when the pest has reached a certain destructive phase. Do not spray because of its mere presence.

6. Choose botanical pesticides, such as nicotine, rotenone and pyrethrum because they are biodegradable and very much less expensive. In fact they can be formulated on the farm. Ask your agriculturist how.
Sayote (Sechium edule) is seldom sprayed, it grows naturally on fences and hillsides

Here are additional tips:

1. Do not harvest newly sprayed crops even if the market is good. Samples of pechay (Brassica chinensis) coming from four Metro Manila markets showed residues of organophosphate insecticides. One is positive in 15 pechay for methyl parathion (0.1 mg/kg), and one is positive in 15 for endosulfan (.01 mg/kg).

2. Washing may help reduce the poisonous residue, but systemic poisons remain in the body of the plant. Avoid eating vegetables, which are known to be heavily protected with pesticide.

3. There are laboratories that determine pesticides residue – Pesticide Analytical Laboratory of the Bureau of Plant Industry, and the Pesticide Residue Laboratory of UPLB, Food Development Center of NFA, DOST, Siliman University and the Philippine Atomic Research Center. If you are in doubt with your favorite vegetables, consult any of these centers.

4. Better yet, plant your own vegetables and practice organic gardening. Spend time outdoor with your plants. Enjoy true freshness of vegetables. And one thing you are sure of. They are pesticide-free.

But if you do not have time and space, have the list of pesticide-free vegetables always ready on hand. They are not only health-friendly but environment-friendly as well, and they are where the Pierian spring of long and happy life flows. ~

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