Protecting our crops against pests and diseases has been our biggest challenge so far. In our first six months of farming, we lost nearly 75% of our harvestable crops to leaf miners, aphids, and bacterial diseases. We tried every solution we knew of to save our vegetables, from spraying neem oil to building shelters for our vegetables, but nothing seemed to work. Some farmer colleagues suggested that we use synthetic chemical pesticides to quickly kill some of the pests but we were determined to stay organic for the future health of our plants and soil. In the end, we had to accept that pest and disease damage is normal in farming; what matters is how to make the damage as little as possible.
After this experience, we began to study in earnest why and how pests attack plants and how plants defend themselves. We discovered that plants without enough water, sunlight, and nutrients become weak and vulnerable to pests. They lack the energy to release chemicals and substances that attract bigger insects like wasps to come and hunt the attackers. We started seeing our farm as not just a land with soil to grow vegetables on but a complex ecosystem containing different relationships between plants, animals, insects, and microscopic organisms. Vegetables were one small part of a large food chain we could not see.
With this new understanding of organic farming, we have shifted our focus from responding to pests and diseases to preventing them. Our strategy now is to follow what is known as holistic pest management, where we focus on environmental design, vegetable health, and routine inspections to prevent pests and diseases from colonising large areas of our farm. We share with you our experiences below.
Controlling pest outbreaks
Common pests like aphids, leaf miners, white flies, and caterpillars are a normal sight on our farm. We see them throughout the year but only in small numbers on patches of our gazunywet (watercress), radish, and roselle leaves. Although they do some physical damage to these vegetables, for example by turning the leaves yellow and creating holes in them, they do not cause much damage because their numbers are small.
We believe their numbers are small because we make it difficult for them to establish themselves on our farm. These pests, like all living things, need food to survive and safe shelter to rest and reproduce. We have tried to limit their food and shelter by doing the following things:
1. We grow alternating rows of vegetables. For example, under one of our roofs, we have three vegetable beds. We plant one row of lettuce, one row of kale, and one row of tarragon. By mixing up the vegetables in one area, we reduce the availability of food for each type of pest. A leaf miner might like to eat lettuce leaves but not kale or tarragon, so it cannot feed beyond the row of lettuce, preventing the leaf miner from colonising the entire area under the roof.
2. We attract beneficial insects like spiders, ladybugs, and wasps and animals such as frogs and lizards near our vegetables to eat up the pests. We do this by planting flowers such as marigolds and sunn hemp, and fruiting shrubs like eggplants and chilis, near our vegetable beds. These plants provide nectar, another food source, and shelter for the beneficial insects and animals.
3. We spray our vegetables with a diluted solution of neem extract once a week. The neem scent acts as a deterrent for the pests and sometimes kills them if they happen to be on the leaves we are spraying.
Making our plants stronger
After establishing an environment that promotes biodiversity and balance, we focus on improving the immune system of our vegetables. Plants have their own defense mechanisms against pests and diseases, which activate when they get attacked or receive chemical signals from nearby plants that are getting attacked. We try to boost our plants’ immune systems by making sure they are adequately watered every day and get the nutrients they need from the compost and animal manures we feed them. We inspect our plants regularly, especially the leaves and stems, to check for signs of nutrient deficiencies and replenish them as fast as we can.
Managing bacteria and viruses is probably the most difficult aspect of our system because we cannot see the pathogens. The most common bacteria we have found are the ones that affect amaranth, blanketing them completely and weakening them, and bacterial blight that produces yellow spots on the gazunywet leaves. They are more stubborn than insect pests and spread very quickly. To manage these we apply compost and add Effective Microorganisms (EM) to soil in the belief that the good bacteria will cancel out the disease causing bacteria in the soil. Sadly, sometimes we do not see the bacterial infection signs until they have spread over a large area. By the time we respond, the plants cannot be rescued. In these circumstances, we let the infected soil rest and recuperate by growing sunn hemp or another type of bean to add nitrogen to the soil and let the bacteria and viruses die out.
Learning from experience
We continue to observe which months bring what types of pests and diseases. So far the monsoon season has brought the most diseases because of the wetness and humidity, which make it easy for pathogens to spread from plant to plant as the water splashes around – they ride the water from plant to plant. In the drier months we see insect pests.
Our aim is to continue building up the diversity on our farm, in terms of plants, and to keep the soil moist and packed with living things/microbes so there can be a natural balance between the good and bad bacteria.