Combate natural I - caldas
Autor: Wedis | Publicado: 2012-07-25T10:57:00-03:00

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A agricultura
orgânica é aquela que não utiliza agrotóxicos nas plantações. Isso é ótimo,
pois é mais seguro para quem planta e para quem consome. No entanto, é também
um constate desafio para o agricultor, que precisará combater pragas e doenças
sem pesticidas.



Para resolver esta
questão, algumas estratégias são utilizadas. Um exemplo é o emprego de caldas,
um tipo de defensivo alternativo. Elas são feitas a partir de produtos naturais
e alguns componentes químicos que não causam prejuízos à saúde e ao meio
ambiente, como enxonfre e cal virgem adicionados em pequenas concentrações.



Uma das mais
conhecidas é a calda bordalesa, que é obtida pela mistura de solução de sulfato
de cobre com suspensão de cal virgem ou hidratado. A mistura é usada para
combater fungos comuns, como o fungo pinta preta, recorrente nas culturas de
tomate e batata.



De acordo com o
fitossanitarista da Empresa de Pesquisa Agropecuária do Estado do Rio de
Janeiro, (Pesagro-Rio), Luiz Augusto de Aguiar, há evidencias de que a calda já
era usada na Europa, no início do século XIX, para o controle de doenças
fúngicas. Mesmo contendo elementos como cobre e cal, seu uso na agricultura orgânica
é permitido por sua baixa toxidade e por contribuir para o equilíbrio
nutricional das plantas, ao fornecer cálcio o cobre.



O pesquisador diz que essas misturas tem se
mostrado muito eficientes, tanto em experimentos em estufas quanto no campo, e
tornam-se ainda mais eficazes se aliadas aos métodos de agrobiodiversidade, que
já deixa o solo mais nutritivo e fortalecido.

Wedis Martins

Fonte: revista Rio Pesquisa - Faperj