ORGANIC FARMING COURSE AGRO-ECONOMY
8 1 NATURAL PETICIDES – 8.17 - OTHER PRACTICES FOR DISEASE
CONTROL
Ø Sulphur
is mostly used
against plant diseases like powdery mildew, downy mildew and other diseases.
The key to its efficacy is that it prevents spore germination. For this reason,
it must be applied prior to disease development for effective results. Sulphur
can be applied as a dust or in liquid form. It is not compatible with other
pesticides. Lime-sulphur is formed when lime is added to sulphur to help it
penetrate plant tissue. It is more effective than elemental sulphur at lower
concentrations. However, the odour of rotten eggs usually discourages its use
over extensive fields.
Ø Bordeaux
mixture (Copper sulphate and
lime) has been successfully used for over 150 years, on fruits, vegetables and
ornamentals. Unlike sulphur, Bordeaux mixture is both fungicidal and
bactericidal. As such, it can be effectively used against diseases such as leaf
spots caused by bacteria or fungi, powdery mildew, downy mildew and various
anthracnose pathogens. The ability of Bordeaux mixture to persist through rains
and to adhere to plants is one reason it has been so effective. Bordeaux
mixture contains copper sulphate, which is acidic, and neutralized by lime (calcium
hydroxide), which is alkaline.
Recommendations
to farmers on preparation of Bordeaux mixture: Bordeaux mixture comes in several formulations. One
of the most popular, effective and least phytotoxic formulations for general
use is the following formulation: Mix 90 g of blue copper sulphate with 4,5 L
of water (in a non-metallic container). In another non-metallic container, mix
125 grams of slaked lime with 4.5 litres of water. Stir both, mix both
solutions, and stir again. This formulation was developed in recognition of the
fact that copper, like sulphur, is phytotoxic and that the level of toxicity is
related to the age of plant tissue being treated. Application of Bordeaux
during hot weather (above 29,5° C or 1,5° C) may cause yellowing and leaf drop.
Additionally, leaf burn can occur if it rains soon after a Bordeaux
application. Care should be taken when applying this fungicide to young, tender
leaves of fruit trees. Do not apply Bordeaux mixture to corn or sorghum, which
are described as copper-sensitive plants. There are other, very common and
cheap copper formulations available: copper hydroxide and copper oxychloride.
They are accepted in organic farming provided that the number of applications
is strictly followed and a proper soil amendment is observed to prevent copper
accumulation in the soil.
Ø Acidic
clays have a fungicidal
effect due to aluminium oxide or aluminium sulphate as active agents. They are
used as an alternative to copper products but, are often less efficient.
Ø Milk
has also been used
against blights, mildew, mosaic viruses and other fungal and viral diseases.
Spraying every 10 days with a mixture of 1 L of milk to 10 to 15 L of water is
effective.
Ø Baking
soda has been used to
control mildew and rust diseases on plants. Spray with a mixture of 100 g of
baking or washing soda with 50 g of soft soap. Dilute with 2 L of water. Spray
only once and leave as long gaps as possible (several months). Do not use
during hot weather and test the mixture on a few leaves because of possible
phytotoxic effects.
Many plant
extracts are known to have fungicidal effects. Onion and garlic are effective
against many diseases such as mildew and fungal and bacterial diseases. Mexican
and African marigold act as a crop “strengthened” to help potatoes, beans,
tomatoes and peas resist fungal diseases such as mildew. The leaves of pawpaw
(Carica papaya) and sweet basil
have a general fungicidal effect. Many other plant species are known to have
fungicidal effects. Traditional knowledge might be of help to amend the range
of plant extracts in each region.
KOZI YA KILIMO HAI
KILIMO-UCHUMI
8 0 WADUDU – 8.17 -
TABIA NYINGINE ZA KUDHIBITI MAGONJWA
Sulfuri hutumika zaidi dhidi ya magonjwa ya mimea kama vile ukungu, ukungu na magonjwa mengine. Ufunguo wa ufanisi wake ni kuzuia kuota kwa spore. Kwa sababu hii, lazima itumike kabla ya maendeleo ya ugonjwa kwa matokeo ya ufanisi. Sulfuri inaweza kutumika kama vumbi au katika hali ya kioevu. Haiendani na dawa zingine za wadudu. Chokaa-sulphur huundwa wakati chokaa kinaongezwa kwenye sulfuri ili kusaidia kupenya tishu za mimea. Ni bora zaidi kuliko sulfuri ya msingi k
Mchanganyiko wa Bordeaux (Copper sulphate na
chokaa) umetumika kwa mafanikio kwa zaidi ya miaka 150, kwenye matunda, mboga
mboga na mapambo. Tofauti na salfa, mchanganyiko wa Bordeaux ni wa kuua na kuua
bakteria. Kwa hivyo, inaweza kutumika kwa ufanisi dhidi ya magonjwa kama vile
madoa ya majani yanayosababishwa na bakteria au fangasi, ukungu wa unga, ukungu
na vimelea mbalimbali vya magonjwa ya anthracnose. Uwezo wa mchanganyiko wa
Bordeaux kuendelea kupitia mvua na kuambatana na mimea ni sababu moja umekuwa
mzuri sana. Mchanganyiko wa Bordeaux una sulphate ya shaba, ambayo ni
tindikali, na haipatikani na chokaa (hidroksidi ya kalsiamu), ambayo ni ya
alkali.
Mapendekezo kwa
wakulima juu ya utayarishaji wa mchanganyiko wa Bordeaux: Mchanganyiko wa
Bordeaux huja katika uundaji kadhaa. Mojawapo ya uundaji maarufu zaidi, wenye
ufanisi na mdogo wa phytotoxic kwa matumizi ya jumla ni uundaji ufuatao:
Changanya 90 g ya sulphate ya shaba ya bluu na 4,5 L za maji (katika chombo
kisicho na metali). Katika chombo kingine kisicho na metali, changanya gramu
125 za chokaa kilichopigwa na lita 4.5 za maji. Koroga zote mbili, changanya suluhu zote mbili, na
ukoroge tena. Muundo huu ulitengenezwa kwa kutambua ukweli kwamba shaba, kama
salfa, ina sumu ya fitoksi na kwamba kiwango cha sumu kinahusiana na umri wa
tishu za mmea kutibiwa. Uwekaji wa Bordeaux wakati wa joto (zaidi ya 85° F au
30° C) unaweza kusababisha manjano na kushuka kwa majani. Zaidi ya hayo,
kuchomwa kwa majani kunaweza kutokea ikiwa mvua inanyesha mara baada ya maombi
ya Bordeaux. Uangalifu unapaswa kuchukuliwa wakati wa kutumia dawa hii ya kuvu
kwa majani machanga na laini ya miti ya matunda. Usitumie mchanganyiko wa
Bordeaux kwenye mahindi au mtama, ambayo inaelezwa kuwa mimea inayoguswa na
shaba. Kuna uundaji mwingine, wa kawaida sana na wa bei nafuu wa shaba
unaopatikana: hidroksidi ya shaba na oksikloridi ya shaba. Zinakubalika katika
kilimo-hai mradi tu idadi ya maombi inafuatwa kikamilifu na marekebisho sahihi
ya udongo yanazingatiwa ili kuzuia mkusanyiko wa shaba kwenye udongo.
Udongo wenye asidi huwa na athari ya kuua ukungu
kutokana na oksidi ya alumini au salfa ya alumini kama mawakala hai. Zinatumika
kama mbadala kwa bidhaa za shaba lakini, mara nyingi hazifanyi kazi vizuri.
Maziwa pia yametumika dhidi ya ukungu, ukungu, virusi
vya mosaic na magonjwa mengine ya fangasi na virusi. Kunyunyizia kila siku 10
kwa mchanganyiko wa lita 1 ya maziwa hadi lita 10 hadi 15 za maji ni nzuri.
Soda ya kuoka imetumika kudhibiti magonjwa ya ukungu na
kutu kwenye mimea. Nyunyiza na mchanganyiko wa 100 g ya kuoka au kuosha soda na
50 g ya sabuni laini. Punguza na 2 L ya maji. Nyunyizia dawa mara moja tu na
uache mapengo marefu iwezekanavyo (miezi kadhaa). Usitumie wakati wa hali ya
hewa ya joto na jaribu mchanganyiko kwenye majani machache kwa sababu ya athari
zinazowezekana za phytotoxic.
Extracts nyingi za mimea
zinajulikana kuwa na athari za fungicidal. Vitunguu na kitunguu saumu ni bora
dhidi ya magonjwa mengi kama vile ukungu na magonjwa ya fangasi na bakteria.
Marigold ya Mexico na Afrika hufanya kama zao "iliyoimarishwa"
kusaidia viazi, maharagwe, nyanya na mbaazi kupinga magonjwa ya ukungu kama
vile ukungu. Majani ya
papai (Carica papai) na basil tamu yana athari ya jumla ya kuvu. Aina nyingine
nyingi za mimea zinajulikana kuwa na athari za fungicidal. Maarifa ya kimapokeo
yanaweza kusaidia kurekebisha aina mbalimbali za dondoo za mimea katika kila
eneo.
