February 20, 2024


Mar Alonso is a biologist and a specialist in phytosanitary control of plants, which means that she knows about all those bugs and diseases that can harm the species that are cared for at home. She passionately carries out her work at JM Escolar, in Fuenlabrada, a nursery that produces horticultural plants that also sells all kinds of garden products. Between substrates, fertilizers, seeds and indoor plants, Alonso covers with her usual kindness and professionalism the aspects that must be taken into account in the maintenance of our vegetables.

ASK. He knows a while about bugs that drive gardeners upside down.

ANSWER. I have to say that despite years of experience advising pests and diseases, you still learn something new every day. And the typical elderly couple who confess to having a “big problem” still causes me great tenderness and with trembling hands shows you the little aluminum foil package where they neatly bring you some yellow leaves from an orange tree or those of a cherry tree that has been preyed on. of the aphid.

Q. What is the most common concern for amateurs and professionals in the cultivation of plants? Is there a difference between one and the other when it comes to perceiving phytosanitary problems?

R. In general, in professionals —both farmers and gardeners— economic motivation prevails since plants are their source of income. They try to stay ahead of problems, learn from their mistakes, and make their business profitable. However, fans get involved in a more emotional way, they love their plants and try to give them the best care. Some of these plants are heirlooms from loved ones, so they have great sentimental value.

Q. Do pests and diseases in plants depend on how the weather year comes?

R. Definitely. Rainy springs will bring us problems with fungi and a large number of aphids on the exuberant vegetation, to give way to the attack of caterpillars, as temperatures stabilize and the days lengthen. Population explosions will occur in dry and hot summers, as more eggs are deposited and cycles are shortened. The red spider mite, the whitefly and thrips —small black or brown neopterous insects— will run wild, testing our patience.

Q. What is it that benefits the aphid, for example, which is one of the most common pests in gardening?

R. The aphid deforms the leaves of plants, filling them with a sticky honeydew that attracts ants and fungi. In addition, it can inject viruses and toxins that further complicate the situation. To avoid this, we must limit the use of mineral fertilizers rich in nitrogen, since they produce excess growth in the plant. It is there where the aphid feeds easily; for this reason, fertilizer based on organic matter is more appropriate. On the other hand, we will promote the presence of their natural predators by installing Hotels of useful fauna, such as flowers and aromatic plants, and, if necessary, we will apply a treatment with products that respect bees and other insects, such as potassium soap, neem oil —a vegetable oil extracted from fruits and neem tree seeds—, or a slurry—natural fertilizer— from nettles.

Mar Alonso surrounded by plants in the JM Escolar nursery in Fuenlabrada (Madrid).
Mar Alonso surrounded by plants in the JM Escolar nursery in Fuenlabrada (Madrid).Patricia Manzanero

Q. What diseases are most often found in a garden?

R. Basically, it will depend on the plants that make up that garden. Hence the importance of a careful selection when planning it, avoiding species a priori conflictive in terms of pests and diseases or that require a high consumption of water, given the current situation.

Q. Is climate change being felt in the appearance or recession of pests and diseases?

R. The increase in temperature favors the establishment of tropical species in areas where they could not live before, with the consequent loss of biodiversity and alteration of habitats. The dispersion and intensity with which pests will affect, as a consequence of climate change, is a problem of the first magnitude that puts global food production at risk. Therefore, we must act before it is too late. As Martin Luther King, American Baptist minister and activist, said: “If I knew that the world would end tomorrow, I would still plant a tree today.”

Q. It is surprising how over the years new problems appear in plants that were not present before.

R. In many cases, indiscriminate treatment with chemical synthesis insecticides has caused the appearance of resistance, which renders control treatments ineffective. On the other hand, the introduction of new pests is a phenomenon that has been favored by international trade and global warming, with serious economic and environmental consequences that are difficult to solve. Thus, since the middle of the last century, we have been fighting against pests of different origins, such as phylloxera —parasite of the vine—, the red louse in citrus fruits, the laurel mealybug or the red palm weevil, among many others.

Q. What basic first-aid kit should be kept at home to care for plants?

R. In Spain we have large biotech companies, such as Seipasa and Idai Nature, with a wide variety of zero-waste products for your care. For the most handy, and without leaving the kitchen of our houses, we have remedies for many of the usual problems in the orchard and garden. Thus, to fight fungi we could make preparations with chamomile, whole milk, baking soda or horsetail. If our problem is insects, garlic, onion, chili peppers, vinegar, parsley, citrus peels or soap dilutions will be of great help. Even eggshells and beer will help us against snails and slugs. We don’t have to spend a lot to take care of our plants.

Q. What place does integrated control and biological control occupy in current gardens?

R. In general terms, it consists of the use of living organisms or their products to fight pests and diseases. Thus, we can control pests by promoting or introducing their predators, as well as pathogenic microorganisms for the pest. The use of sterile males has also been beneficial, as have pheromone traps. The aim is not so much the total elimination of pests, but to keep them within tolerance levels with minimal intervention. And all this, with the premise of protecting the environment and biodiversity.

A biocide-free garden becomes a safer place for wildlife and for the people who enjoy it.
A biocide-free garden becomes a safer place for wildlife and for the people who enjoy it.Edward Beard

Q. What becomes of a garden in which there is a lower presence of chemical products?

R. In a place where we can enjoy nature with our family and pets, free of toxins, where we can safely collect fruits, herbs and flowers for our consumption, with fertile soil full of life, an army of insectivorous birds and auxiliary fauna that keep pests at bay. In short, an ecosystem in harmony where each organism has its importance and its place.

Q. Then there is the controversial issue of herbicides…

R. Since the 1970s, when the use of the herbicide glyphosate was introduced, thousands of tons have been dumped, contaminating land and water around the world. Its relationship with cancer, developmental delays, intestinal diseases and liver and kidney damage is recognized, in addition to negatively affecting the reproductive, neurological and hormonal systems. It seems that on December 15, 2023, its use will finally be prohibited, which opens up a hopeful horizon of agroecological transition in the management of weeds. From here, we hope that alternative environmentally friendly techniques will be applied, such as mechanical, manual and thermal methods, ecological herbicides and the creation of plant covers that prevent soil erosion and increase biodiversity.

Q. In your day to day, what has helped you to have such a broad vision of the phytosanitary sector?

R. I believe that the agricultural practices of the last 50 years have created environmental damage, in many cases irreversible. With the knowledge acquired, now it is time to change, for the good of all.

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