8 1 NATURAL PESTICIDES – 8.12 – BOTANICALS

 ORGANIC FARMING COURSE AGRO-ECONOMY

8 1 NATURAL PESTICIDES – 8.12 – BOTANICALS

 

Some plants contain components that are toxic to insects. When extracted from the plants and applied on infested crops, these components are called botanical pesticides or botanicals. The use of plant extracts to control pests is not new. Rotenone (Derris sp.), nicotine (tobacco), and pyrethrins (Chrysanthemum sp.) have been used widely both in small-scale subsistence farming as well as in commercial agriculture.

Most botanical pesticides are contact, respiratory, or stomach poisons. Therefore, they are not very selective, but target a broad range of insects. This means that even beneficial organisms can be affected. Yet the toxicity of botanical pesticides is usually not very high and their negative effects on beneficial organisms can be significantly reduced by selective application. Furthermore, botanical pesticides are generally highly bio-degradable, so that they become inactive within hours or a few days. This reduces again the negative impact on beneficial organisms, and they are relatively environmentally safe compared to chemical pesticides:

The impact of chemical pesticides on natural enemies: the y-axis shows the sizes of the pest and predator populations, the x-axis their development in time

FIGURE 8-12 - THE IMPACT OF CHEMICAL PESTICIDES ON NATURAL ENEMIES

KOZI YA KILIMO HAI KILIMO-UCHUMI

8 1 DAWA ASILI ZA WAdudu – 8.12 -BOTANICALS

Mimea mingine ina vipengele ambavyo ni sumu kwa wadudu. Inapotolewa kutoka kwa mimea na kutumika kwenye mazao yaliyoshambuliwa, vipengele hivi huitwa dawa za mimea au mimea. Matumizi ya dondoo za mimea kudhibiti wadudu sio jambo geni. Rotenone (Derris sp.), nikotini (tumbaku), na pyrethrins (Chrysanthemum sp.) zimetumika sana katika ukulima mdogo na pia katika kilimo cha biashara.

Dawa nyingi za dawa za mimea ni za kugusa, kupumua, au sumu ya tumbo. Kwa hiyo, sio kuchagua sana, lakini hulenga aina mbalimbali za wadudu. Hii ina maana kwamba hata viumbe vyenye manufaa vinaweza kuathiriwa. Hata hivyo sumu ya viuatilifu vya mimea kwa kawaida sio juu sana na athari zake mbaya kwa viumbe vyenye manufaa zinaweza kupunguzwa kwa kiasi kikubwa kwa matumizi ya kuchagua. Zaidi ya hayo, dawa za kuulia wadudu za mimea kwa ujumla zinaweza kuharibika kwa kiasi kikubwa, hivyo basi hazifanyi kazi ndani ya saa au siku chache. Hii inapunguza tena athari mbaya kwa viumbe vyenye faida, na ni salama kwa mazingira ikilinganishwa na dawa za kemikali:

Sasa inashughulikia masomo yote 500 yenye mazao, mitishamba na maelezo ya matunda katika Kiingereza na Maswali

Athari za viuatilifu vya kemikali kwa maadui asilia: mhimili y huonyesha saizi ya wadudu na wanyama wanaowinda wanyama wengine, mhimili wa x maendeleo yao kwa wakati.

KIELELEZO 8-12 - ATHARI ZA VIUMBE VYA KEMIKALI KWA MAADUI WA ASILI.