8 0 PESTS – 8.7 - PROMOTING AND MANAGING NATURAL ENEMIES

 

 ORGANIC FARMING COURSE AGRO-ECONOMY

8 0 PESTS – 8.7 - PROMOTING AND MANAGING NATURAL ENEMIES

 

The natural enemies of pests are other organisms (fungi, bacteria, viruses, insect predators, and insect parasiticides) which kill pest. Therefore, the organic farmer should try to conserve natural enemies already present in the crop environment and enhance their impact. This can be achieved with the following methods:

•       Minimize the application of natural pesticides (chemical pesticides anyway are not per-mitted in organic farming).

•       Allow some pests to live in the field which will serve as food or host for natural enemies.

•       Establish a diverse cropping system (e.g. mixed cropping).

•       Include host plants providing food or shelter for natural enemies (e.g. flowers which adult beneficial insects feed on).

There are many possibilities to enhance floral diversity within and along the boundaries of crop fields:

§  Hedges - Use indigenous shrubs known to attract pest predators and parasitoids by offering nectar, pollen, alternative hosts and/or preys. Most flowering shrub species have this property. However, care should be taken to not use plant species known to be alternative hosts of pests or diseases.

§  Beetle banks - Strips of grass in the neighbourhood of crop fields harbour different natural pest enemy groups like carabids, staphylinid beetles and spiders. In order to lower the risk of weeds and plants known as host plants of crop pests and diseases, one to three native grass species can be sown in strips of 1 to 3 m.

§  Flower strips - Use indigenous flowering plant species known to attract predators and parasitoids by offering nectar, pollen, alternative hosts and/or preys. Most flowering plant species have this property. However, care should be taken not to use alternative hosts of pests or diseases. Three to five native flowering plant species can be sown in well-prepared seed beds, arranged in strips of 1 to 3 m on the boundary of the crop field. After flowering, seeds can be collected to renew the strip or create new ones. 

§  Companion plants - Natural pest enemies can also be attracted by companion plants within a crop. These companion plant species can be the same as used in the flower strips. A few (1 or 2 per 10 m²) flowering companion plants within a crop serve as a ‘service station’ for natural pest enemies.

 

 

KOZI YA KILIMO HAI KILIMO-UCHUMI

8 0 WADUDU – 8.7 - KUKUZA NA KUWASIMAMIA ADUI ASILI

 

Maadui wa asili wa wadudu ni viumbe vingine (fangasi, bakteria, virusi, wadudu wanaokula wadudu, na dawa za kuua wadudu) ambao huua wadudu. Kwa hiyo, mkulima wa kilimo-hai anapaswa kujaribu kuhifadhi maadui wa asili ambao tayari wapo katika mazingira ya mazao na kuongeza athari zao. Hii inaweza kupatikana kwa njia zifuatazo:

• Punguza uwekaji wa viuatilifu asilia (viuatilifu vya kemikali hata hivyo haviruhusiwi katika kilimo hai).

• Ruhusu baadhi ya wadudu kuishi kwenye shamba ambalo litakuwa chakula au mwenyeji wa maadui wa asili.

• Anzisha mfumo wa upandaji miti tofauti (k.m. upandaji miti mchanganyiko).

• Jumuisha mimea mwenyeji inayotoa chakula au makazi kwa maadui wa asili (k.m. maua ambayo wadudu wenye manufaa wazima hula).

Kuna uwezekano mwingi wa kuboresha uanuwai wa maua ndani na kando ya mipaka ya mashamba ya mazao:

 Ua - Tumia vichaka vya kiasili vinavyojulikana kuvutia wadudu waharibifu na vimelea kwa kutoa nekta, chavua, mwenyeji mbadala na/au mawindo. Aina nyingi za vichaka vya maua vina mali hii. Hata hivyo, tahadhari inapaswa kuchukuliwa ili kutotumia aina za mimea zinazojulikana kuwa mwenyeji wa wadudu au magonjwa mbadala.

 Maeneo ya mende - Sehemu za nyasi karibu na mashamba ya mazao huhifadhi makundi mbalimbali ya adui wadudu waharibifu kama vile carabids, mende wa staphylinid na buibui. Ili kupunguza hatari ya magugu na mimea inayojulikana kama mimea mwenyeji wa wadudu na magonjwa ya mazao, spishi moja hadi tatu za nyasi asili zinaweza kupandwa kwenye vipande vya mita 1 hadi 3.

 Vipande vya maua - Tumia spishi za mimea ya kiasili inayotoa maua inayojulikana kuvutia wanyama wanaowinda wanyama wengine na vimelea kwa kutoa nekta, chavua, mwenyeji mbadala na/au mawindo. Aina nyingi za mimea ya maua zina mali hii. Hata hivyo, uangalizi unapaswa kuchukuliwa kutotumia majeshi mbadala ya wadudu au magonjwa. Aina tatu hadi tano za mimea asilia zinazotoa maua zinaweza kupandwa kwenye vitanda vya mbegu vilivyotayarishwa vyema, vikiwa vimepangwa kwa vipande vya mita 1 hadi 3 kwenye mpaka wa shamba la mazao. Baada ya maua, mbegu zinaweza kukusanywa ili kufanya upya ukanda au kuunda mpya.

 Mimea shirikishi - Maadui wa wadudu wa asili wanaweza pia kuvutiwa na mimea shirikishi ndani ya zao. Aina hizi za mimea shirikishi zinaweza kuwa sawa na kutumika katika vipande vya maua. Mimea michache (1 au 2 kwa kila m2 10) inayochanua maua hutumika kama 'kituo cha huduma' kwa maadui wa asili wa wadudu.

8 0 PESTS – 8.8 - MECHANICAL CONTROL OF PESTS

 

  ORGANIC FARMING COURSE AGRO-ECONOMY

 8 0 PESTS – 8.8 - MECHANICAL CONTROL OF PESTS

Mass-trapping of pests is an additional control measure. They often can easily be built with cheap material. Some examples include:

Light traps can be used to catch moths such as armyworms, cutworms, stem borers and other night flying insects. Light traps are more efficient when placed soon after the adult moths start to emerge but before they start laying eggs. However, light traps have the disadvantage of attracting a wide range of insect species. Most of the attracted insects are not pests. In addition, many insects that are attracted to the area around the light traps (sometimes from considerable distances) do not actually fly into the trap. Instead, they remain nearby, actually increasing the total number of insects in the immediate area. 

Colour and water traps can be used to monitor adult thrips. In some cases, thrips can even be reduced by mass trapping with coloured (blue, yellow or white) sticky traps or water traps in the nursery or field. The colour spectrum of the boards is important for the efficacy of the sticky traps. Bright colours attract more thrips than darker ones. Sticky traps with cylindrical surfaces are more efficient that flat surfaces. They are best placed within a meter of crop level. Traps should not be placed near the borders of fields or near shelter belts.

Water traps should be at least 6 cm deep with a surface area of 250 to 500 cm², and preferably round, with the water level about 2 cm below the rim. A few drops of detergent added to the water ensure that thrips sink and do not drift to the edges and escape. Replace or add water regularly. 

Yellow sticky traps can be used to control whiteflies, aphids and leaf mining flies. Yellow plastic gallon containers mounted upside down on sticks coated with transparent car grease or used motor oil, is one such trap. These should be placed in and around the field at about 10 cm above the foliage. Clean and re-oil when traps are covered with flies. Yellow sticky boards have a similar effect. To use, place 2 to 5 yellow sticky cards per 500 m² field area. Replace traps at least once a week. To make your own sticky trap, spread petroleum jelly or used motor oil on yellow painted plywood (size 30 cm x 30 cm). Place traps near the plants but faraway enough to prevent the leaves from sticking to the board. Note that the yellow colour attracts many insect. Note that the yellow colour attracts many insect species, including beneficial insects, so use yellow traps only when necessary.

Fruit bagging prevents fruit flies from laying eggs on the fruits (Figure 8-8). In addition, the bag provides physical protection from mechanical injuries (scars and scratches). Although laborious, it is cheap, safe and gives a more reliable estimate of the projected harvest. Bagging works well with melon, bitter gourd, mango, guava, star fruit, avocadoes and banana (plastic bags used).

 

Recommendations to farmers regarding fruit bagging: Cut old newspapers to fruit size and double the layers, as single layers break apart easily. Fold and sew or staple the sides and bottom of the sheets to make a rectangular bag. Blow in the bag to inflate it. Insert one fruit per bag then close the bag and firmly tie the top end of the bag with sisal string, wire and banana fibre or coconut midrib. Push the bottom of the bag upwards to prevent fruit from touching the bag. For example, start bagging the mango fruit 55 to 60 days from flower bloom or when the fruits are about the size of a chicken egg. When using plastic bags (e.g. with bananas), open the bottom or cut a few small holes to allow moisture to dry up. Moisture trapped in the plastic bags damages and/or promotes fungal and bacterial growth that causes diseased fruits. Plastic also overheats the fruit. Bags made of dried plant leaves are good alternatives to plastic.

 

 

 KOZI YA KILIMO HAI KILIMO-UCHUMI

 8 0 WADUDU – 8.8 - UDHIBITI WA MITAMBO YA WADUDU

Ukamataji wa wadudu kwa wingi ni hatua ya ziada ya kudhibiti. Mara nyingi zinaweza kujengwa kwa urahisi na nyenzo za bei nafuu. Baadhi ya mifano ni pamoja na:

Mitego nyepesi inaweza kutumika kukamata nondo kama vile viwavi jeshi, minyoo, vipekecha shina na wadudu wengine wanaoruka usiku. Mitego nyepesi huwa na ufanisi zaidi inapowekwa mara tu baada ya nondo waliokomaa kuanza kujitokeza lakini kabla ya kuanza kutaga mayai. Hata hivyo, mitego ya mwanga ina hasara ya kuvutia aina mbalimbali za wadudu. Wengi wa wadudu wanaovutia sio wadudu. Kwa kuongeza, wadudu wengi wanaovutiwa na eneo karibu na mitego ya mwanga (wakati mwingine kutoka umbali mkubwa) hawana kweli kuruka kwenye mtego. Badala yake, wanabaki karibu, na kuongeza idadi ya wadudu katika eneo la karibu.

Mitego ya rangi na maji inaweza kutumika kufuatilia thrips ya watu wazima. Katika baadhi ya matukio, thrips inaweza hata kupunguzwa kwa kunasa kwa wingi kwa mitego ya rangi (bluu, njano au nyeupe) yenye kunata au mitego ya maji kwenye kitalu au shamba. Wigo wa rangi ya bodi ni muhimu kwa ufanisi wa mitego ya fimbo. Rangi mkali huvutia thrips zaidi kuliko nyeusi. Mitego ya kunata yenye nyuso za silinda ni bora zaidi kuliko nyuso tambarare. Wao ni bora kuwekwa ndani ya mita ya kiwango cha mazao. Mitego haipaswi kuwekwa karibu na mipaka ya mashamba au karibu na mikanda ya hifadhi.

Mitego ya maji inapaswa kuwa na kina cha angalau 6 cm na eneo la 250 hadi 500 cm2, na ikiwezekana pande zote, na kiwango cha maji karibu 2 cm chini ya ukingo. Matone machache ya sabuni yanayoongezwa kwenye maji huhakikisha kwamba thrips huzama na hazielekei kwenye kingo na kutoroka. Badilisha au kuongeza maji mara kwa mara.

Mitego ya manjano yenye kunata inaweza kutumika kudhibiti inzi weupe, vidukari na nzi wa kuchimba majani. Vyombo vya manjano vya galoni za plastiki vilivyowekwa juu chini juu ya vijiti vilivyopakwa grisi ya gari inayoonekana wazi au mafuta yaliyotumika ya gari, ni mtego mmoja kama huo. Hizi zinapaswa kuwekwa ndani na kuzunguka shamba kwa umbali wa cm 10 juu ya majani. Safisha na utie mafuta tena mitego inapofunikwa na nzi. Bodi za nata za manjano zina athari sawa. Ili kutumia, weka kadi 2 hadi 5 za njano za kunata kwa kila eneo la 500 m2 la uwanja. Badilisha mitego angalau mara moja kwa wiki. Ili kutengeneza mtego wako unaonata, panua jeli ya petroli au mafuta ya gari yaliyotumika kwenye plywood iliyopakwa rangi ya manjano (ukubwa wa sm 30 x 30 cm). Weka mitego karibu na mimea lakini kwa mbali ili kuzuia majani kushikamana na ubao. Kumbuka kwamba rangi ya njano huvutia wadudu wengi. Kumbuka kwamba rangi ya njano huvutia aina nyingi za wadudu, ikiwa ni pamoja na wadudu wenye manufaa, hivyo tumia mitego ya njano tu wakati wa lazima.

Ufungaji wa matunda huzuia nzi wa matunda kutaga mayai kwenye matunda (Mchoro 8-7). Kwa kuongeza, mfuko hutoa ulinzi wa kimwili kutokana na majeraha ya mitambo (makovu na scratches). Ingawa ni ngumu, ni nafuu, salama na inatoa makadirio ya kuaminika zaidi ya makadirio ya mavuno. Bagging hufanya kazi vizuri na tikiti, kibuyu chungu, embe, mapera, tunda la nyota, parachichi na ndizi (mifuko ya plastiki inatumika).

Mapendekezo kwa wakulima kuhusu kuweka mifuko ya matunda: Kata magazeti ya zamani kwa ukubwa wa matunda na tabaka mara mbili, kwani tabaka moja hutengana kwa urahisi. Pindisha na kushona au kuunganisha pande na chini ya karatasi ili kufanya mfuko wa mstatili. Piga kwenye begi ili uiongezee hewa. Weka tunda moja kwa kila mfuko kisha funga mfuko na ufunge kwa uthabiti ncha ya juu ya mfuko kwa uzi wa mkonge, waya na uzi wa ndizi au katikati ya nazi. Sukuma sehemu ya chini ya begi kwenda juu ili kuzuia matunda kugusa mfuko. Kwa mfano, anza kuweka tunda la embe siku 55 hadi 60 kutoka kuchanua maua au wakati matunda yana ukubwa wa yai la kuku. Unapotumia mifuko ya plastiki (k.m. na ndizi), fungua sehemu ya chini au kata matundu machache ili kuruhusu unyevu kukauka. Unyevu ulionaswa kwenye mifuko ya plastiki huharibu na/au kukuza ukuaji wa fangasi na bakteria ambao husababisha matunda yenye magonjwa. Plastiki pia huzidisha matunda. Mifuko iliyofanywa kwa majani ya mimea kavu ni mbadala nzuri kwa plastiki.

 

8 1 NATURAL PESTICIDES – 8.9 - BIOLOGICAL CONTROL OF PESTS

 

ORGANIC FARMING COURSE AGRO-ECONOMY

8 1 NATURAL PESTICIDES – 8.9 - BIOLOGICAL CONTROL OF PESTS 

 

Biological control is the use of natural enemies to manage populations of pests (such as ladybird beetles, predatory gall midges, hoverfly larvae against aphids and psyllids) and diseases. This implies that we are dealing with living systems, which are complex and vary from place to place and from time to time. 

 

TEXT in the picture:

Population maxima, Number of pests , number of predators

Population dynamics of pests and predators: the y-axis shows the size of the pest and predator populations, the x-axis their development in time

 

KOZI YA KILIMO HAI KILIMO-UCHUMI                                                                           

8.1 DAWA ASILI ZA WADUDU - 8.9 - UDHIBITI WA WADUDU WA KIBIOLOJI

Udhibiti wa kibayolojia ni matumizi ya maadui asilia kudhibiti idadi ya wadudu (kama vile mbawakawa, wadudu waharibifu, mabuu ya hoverfly dhidi ya aphids na psyllids) na magonjwa. Hii ina maana kwamba tunashughulika na mifumo ya maisha, ambayo ni tata na inatofautiana kutoka mahali hadi mahali na mara kwa mara.

TEXT kwenye picha:

Idadi ya watu maxima, Idadi ya wadudu, idadi ya wanyama wanaokula wenzao

Mienendo ya idadi ya wadudu na wanyama wanaowinda wanyama wengine: mhimili wa y unaonyesha saizi ya wadudu na wanyama wanaowinda wanyama wengine, mhimili wa x maendeleo yao kwa wakati.

FIGURE 8-9- POPULATION DYNAMICS OF PESTS AND PREDATORS

 

8 1 NATURAL PESTICIDES – 8.10 - RELEASING NATURAL ENEMIES

 

ORGANIC FARMING COURSE AGRO-ECONOMY

8 1 NATURAL PESTICIDES – 8.10 - RELEASING NATURAL ENEMIES

If populations of natural enemies present in the field are too small to sufficiently control pests, they can be reared in a laboratory or rearing unit. The reared natural enemies are released in the crop to boost field populations and keep pest populations down. There are two approaches to biological control through the release of natural enemies:

•     Preventive release of the natural enemies at the beginning of each season. This is used when the natural enemies could not persist from one cropping season to another due to unfavourable climate or the absence of the pest. Populations of the natural enemy then establish and grow during the season.

•     Releasing natural enemies when pest populations start to cause damage to crops (Figure 8-9). Pathogens are usually used in that way, because they cannot persist and spread in the crop environment without the presence of a host (“pest”). They are also often inexpensive to produce.

 

TEXT in the picture:

•     releasing beneficial insects

•     cards with trichogramma eggs: against maize fruitborer

•     using antaginic microbes

•     BACTERIA: Bazillus thuringensis àagainst catarpillars, beetles, mosquito etc.

•     VIRUSES: NPV àagainst catarpillar

•     FUNGI: Beauveria bassiana àagainst corn boreres

•     NEMATODES: Steinernema carpocapsae -à against cutworms

KOZI YA KILIMO HAI KILIMO-UCHUMI

8 1 DAWA ASILI ZA WAdudu – 8.10 - KUWAACHA MAADUI WA ASILI

Ikiwa idadi ya maadui wa asili waliopo shambani ni ndogo sana kudhibiti wadudu vya kutosha, wanaweza kukuzwa katika maabara au kitengo cha ufugaji. Maadui asilia waliolelewa hutolewa katika zao ili kuongeza idadi ya wadudu na kupunguza idadi ya wadudu. Kuna njia mbili za udhibiti wa kibaolojia kupitia kutolewa kwa maadui asilia:

• Kinga ya kutolewa kwa maadui wa asili mwanzoni mwa kila msimu. Hii inatumika wakati maadui wa asili hawakuweza kuendelea kutoka msimu mmoja wa mazao hadi mwingine kutokana na hali mbaya ya hewa au kutokuwepo kwa wadudu. Idadi ya adui wa asili huanzisha na kukua wakati wa msimu.

• Kuwaachilia maadui wa asili wakati idadi ya wadudu inapoanza kusababisha uharibifu wa mazao (Mchoro 8-9). Pathogens kawaida hutumiwa kwa njia hiyo, kwa sababu hawawezi kuendelea na kuenea katika mazingira ya mazao bila kuwepo kwa mwenyeji ("wadudu"). Pia mara nyingi ni gharama nafuu kuzalisha.

TEXT kwenye picha:

• kutoa wadudu wenye manufaa

• kadi zenye mayai ya trichogramma: dhidi ya mzaa matunda wa mahindi

• kutumia vijidudu vya antaginic

• BACTERIA: Bazillus thuringensis dhidi ya catarpillar, mende, mbu n.k.

• VIRUSI: NPV dhidi ya catarpillar

• FANGASI: Beauveria bassiana dhidi ya vipekecha-mahindi

• NEMATODES: Steinernema carpocapsae - dhidi ya minyoo

 

8 1 NATURAL PESTICIDES - 8.11 - BIOCONTROL OF PLANT DISEASES BY NON-PATHOGENIC FUNGI

 

ORGANIC FARMING COURSE AGRO-ECONOMY

8 1 NATURAL PESTICIDES - 8.11 - BIOCONTROL OF PLANT DISEASES BY NON-PATHOGENIC FUNGI

Natural enemies that kill or suppress pests or diseases are often fungi or bacteria. They are called antagonists or referred to as microbial insecticides or bio-pesticides. Some commonly used antagonistic microbes are:

Ø Bacteria such as Bacillus thuringiensis (Bt). Bt has been available as a commercial microbial insecticide since the 1960s. Different types of Bt are available for the control of caterpillars and beetles in vegetables and other agricultural crops, and for mosquito and black fly control. The bestknown biocontrol agent used in field crops is the bacteria Bacillus thuringiensis var. kurstaki and Bacillus thuringiensis. var. aizawai against diverse lepidopteran pests, and the Bacillus thuringiensis var israeliensis against mosquitoes. Bacillus thuringiensis var kurstaki is produced in local factories in different African countries (e.g. South Africa, Kenya and Mozambique) and can be used against different pests (African armyworm, African bollworm, bean armyworm, beet armyworm, cabbage webworm, cabbage moth, cabbage looper, cotton leafworm, diamondback moth, giant looper, green looper, spiny bollworm, spotted bollworm, pod borers, tomato looper).

Ø Viruses such as NPV (nuclearpolyhedrosis virus), effective for control of several cater-pillar pest species. Every insect species, however, requires a specific NPV-species. An example: The armyworm Spodoptera exigua is a major problem in shallot production in Indonesia. Since experiments showed that SeNPV (NPV specific for S. exigua) provided better control than insecticides, farmers have adopted this control method. Many farmers in West-Sumatra are now producing NPV on-farm. 

Ø Fungi that kill insects, such as Beauveria bassiana. Different strains of this fungus are commercially available. For example: strain Bb 147 is used for control of corn borers (Ostrinia nubilalis and O. furnacaiis) in maize, strain GHA is used against whitefly, thrips, aphids and mealybugs in vegetables and ornamentals. Several species of fungi can occur naturally in ecosystems. For example, aphids can be killed by a green or white coloured fungus during humid weather.

Ø Fungi that work against plant-pathogens. Some examples include: Trichoderma sp., widely used in Asia for prevention of soil-borne diseases such as damping-off and root rots in vegetables (Figure 8-10). Some Trichogramma species against the African bollworm are bred in some laboratories in Africa against lepidopteran pests and aphids.  A successful introduction of the neotropical parasitoid Apoanagyrus lopezi against the cassava mealybug (Phenacoccus manihoti) caused a satisfactory reduction of P. manihoti in most farmers’ fields in Africa. This is one of the success stories of classical biocontrol.

Ø Entomopathogenic nematodes against different weevil species (e.g. Steinernema carpocapsae, Heterorhabditis bacteriophora) and to control soil insects like cutworms (Agrotis spp.) in vegetables

 

TEXT in the picture:

 Biocontrol by Trichoderma harzianum

The fungi species Trichoderma harzianum is known to parasite important plant disease like damping off (Rhizoctonia solani)

Trichoderma species can affect plant diseases by antibiosis and competition

 In addition, Trichoderma works as a growth stimulant and improves yields and product quality 

Some products are available in Africa n countries.

 

KOZI YA KILIMO HAI KILIMO-UCHUMI

8 1 DAWA ASILI 8.11 - UDHIBITI WA UGONJWA WA MIMEA KWA KUPITIA FANGASI WASIO NA MADAWA

 

Maadui asilia wanaoua au kukandamiza wadudu au magonjwa mara nyingi ni fangasi au bakteria. Wanaitwa wapinzani au wanajulikana kama viua wadudu wadogo au viua wadudu. Baadhi ya vijidudu pinzani vinavyotumika sana ni:

 Bakteria kama vile Bacillus thuringiensis (Bt). Bt imekuwa ikipatikana kama dawa ya kibiashara ya kuua wadudu tangu miaka ya 1960. Aina tofauti za Bt zinapatikana kwa udhibiti wa viwavi na mende katika mboga na mazao mengine ya kilimo, na kwa udhibiti wa mbu na nzi weusi. Wakala wa udhibiti wa kibayolojia anayejulikana sana katika mazao ya shambani ni bakteria Bacillus thuringiensis var. kurstaki na Bacillus thuringiensis. var. aizawai dhidi ya wadudu mbalimbali wa lepidoptera, na Bacillus thuringiensis var israeliensis dhidi ya mbu. Bacillus thuringiensis var kurstaki huzalishwa katika viwanda vya ndani katika nchi mbalimbali za Afrika (k.m. Afrika Kusini, Kenya na Msumbiji) na inaweza kutumika dhidi ya wadudu mbalimbali (African armyworm, African bollworm, bean armyworm, beet armyworm, kabichi webworm, nondo ya kabichi, looper ya kabichi. , mdudu wa majani ya pamba, nondo wa diamondback, kitanzi kikubwa, kitanzi cha kijani kibichi, funza wa spiny, funza wenye madoadoa, vipekecha ganda, kitanzi cha nyanya).

 Virusi kama vile NPV (nuclearpolyhedrosis virus), yenye ufanisi katika udhibiti wa spishi kadhaa za wadudu waharibifu. Kila aina ya wadudu, hata hivyo, inahitaji spishi maalum ya NPV. Mfano: Minyoo aina ya Sodoptera exigua ni tatizo kubwa katika uzalishaji wa shaloti nchini Indonesia. Kwa kuwa majaribio yalionyesha kuwa SeNPV (NPV mahususi kwa S. exigua) ilitoa udhibiti bora zaidi kuliko viua wadudu, wakulima wametumia mbinu hii ya kudhibiti. Wakulima wengi katika Sumatra Magharibi sasa wanazalisha NPV shambani.

 Kuvu wanaoua wadudu, kama vile Beauveria bassiana. Aina tofauti za Kuvu hii zinapatikana kibiashara. Kwa mfano: aina ya Bb 147 inatumika kudhibiti vipekecha mahindi (Ostrinia nubilalis na O. furnacaiis) kwenye mahindi, aina ya GHA inatumika dhidi ya nzi weupe, vithrips, aphids na mealybugs kwenye mboga na mapambo. Aina kadhaa za fangasi zinaweza kutokea kwa asili katika mfumo wa ikolojia. Kwa mfano, aphid inaweza kuuawa na Kuvu ya rangi ya kijani au nyeupe wakati wa hali ya hewa ya unyevu.

 Kuvu wanaofanya kazi dhidi ya vimelea vya magonjwa ya mimea. Baadhi ya mifano ni pamoja na: Trichoderma sp., inayotumika sana katika Asia kwa ajili ya kuzuia magonjwa yanayoenezwa na udongo kama vile unyevunyevu na kuoza kwa mizizi kwenye mboga (Mchoro 8-10). Baadhi ya spishi za Trichogramma dhidi ya funza wa Kiafrika huzalishwa katika baadhi ya maabara barani Afrika dhidi ya wadudu waharibifu wa lepidoptera na aphids. Kuanzishwa kwa mafanikio kwa vimelea vya neotropiki Apoanagyrus lopezi dhidi ya mealybug ya muhogo (Phenacoccus manihoti) kulisababisha upungufu wa kuridhisha wa P. manihoti katika mashamba mengi ya wakulima barani Afrika. Hii ni moja ya hadithi za mafanikio za udhibiti wa kibayolojia wa kitambo.



Nematode entomopathogenic dhidi ya spishi tofauti za wadudu (k.m. Steinernema carpocapsae, Heterorhabditis bacteriophora) na kudhibiti wadudu wa udongo kama minyoo (Agrotis spp.) kwenye mboga.

TEXT katika picha: Biocontrol by Trichoderma harzianum

• Kuvu aina ya Trichoderma harzianum inajulikana kwa vimelea vya magonjwa muhimu ya mimea kama vile kunyonya maji (Rhizoctonia solani)

• Spishi za Trichoderma zinaweza kuathiri magonjwa ya mimea kwa antibiosis na ushindani

• Zaidi ya hayo, Trichoderma hufanya kazi kama kichocheo cha ukuaji na kuboresha mavuno na ubora wa bidhaa

• Baadhi ya bidhaa zinapatikana katika nchi za Afrikan

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.

 

                      

8 1 NATURAL PESTICIDES – 8.13 - NEEM SOLUTION

 

 

ORGANIC FARMING COURSE AGRO-ECONOMY

8 1 NATURAL PESTICIDES – 8.13 - NEEM SOLUTION 

 

The preparation and use of botanicals require some know-how, but not much material and infrastructures. It’s a common practice under many traditional agricultural systems. Some commonly used botanicals are:

 NEEM: Neem derived from the neem tree (Azadiracta indica) of arid tropical regions, contains several insecticidal compounds. The main active ingredient is azadiractin, which both deters and kills many species of caterpillars, thrips and whitefly. Both seeds and leaves can be used to prepare the neem solution. Neem seeds contain a higher amount of neem oil, but leaves are available all year. A neem solution loses its effectiveness within about 8 hours after preparation, and when exposed to direct sunlight. It is most effective to apply neem in the evening, directly after preparation, under humid conditions or when the plants and insects are damp. There exist different recipes for the preparation of a neem solution. 

Recommendation to farmers about preparation of neem pesticides: In Ghana, Africa, neem seed kernel extract was tested on cabbage in Farmer trainings and had a very good repelling effect on diamondback moth (Plutella xylostella). Here is their recipe: Pound 30 g neem kernels (that is the seed of which the seed coat has been removed) and mix it in 1 L of water. Leave it overnight. The next morning, filter the solution through a fine cloth and use it immediately for spraying. It should not be further diluted.

Neem cake (ground neem seed or neem kernel powder) has also a considerable potential as a fertilizer and at the same time it will hinder nematode attacks of the crop roots (e.g. tomato). Put neem cake in the planting pit (200g per m2) and mix it with substrate. The neem cake will repel and even kill nematodes and other root pests. Insecticidal agents (azadirachtin) will be translocated to above-ground parts of the plant and help to get rid of pests there.

 

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

 

TEXT in the picture:

·         A. Handful of seeds to a coarse powder or bruise 2 kg of leaves. To make a concentrate.

·         B. Infuse them 25 minutes in hot water or overnight in cold water.

·         C. Working under shade filter the concentrate into a half-filled tank.

Stir in a little soap powder and top up the tank with clean cold water.

·         D. Spray the crop in the late afternoon because neem breakdown in the sunlight.

 

FIGURE 8-13 - PREPARATION OF A NEEM SOLUTION

 

KOZI YA KILIMO HAI KILIMO-UCHUMI

8 1 WADUDU – 8.13 - DAWA ASILI: SULUHISHO LA NEEM

 

Utayarishaji na matumizi ya mimea huhitaji ujuzi fulani, lakini sio nyenzo nyingi na miundombinu. Ni mazoezi ya kawaida chini ya mifumo mingi ya jadi ya kilimo. Baadhi ya mimea inayotumika sana ni:

 NEEM: Mwarobaini unaotokana na mwarobaini (Azadiracta indica) wa maeneo kame ya tropiki, una viambata kadhaa vya kuua wadudu. Kiambatanisho kikuu kinachofanya kazi ni azadiractin, ambayo huzuia na kuua aina nyingi za viwavi, thrips na whitefly. Mbegu na majani yote yanaweza kutumika kuandaa suluhisho la mwarobaini. Mbegu za mwarobaini zina kiasi kikubwa cha mafuta ya mwarobaini, lakini majani yanapatikana mwaka mzima. Myeyusho wa mwarobaini hupoteza ufanisi wake ndani ya takribani saa 8 baada ya kutayarishwa, na unapoangaziwa na jua moja kwa moja. Ni bora zaidi kupaka mwarobaini jioni, moja kwa moja baada ya maandalizi, chini ya hali ya unyevu au wakati mimea na wadudu ni unyevu. Kuna mapishi tofauti ya kuandaa suluhisho la mwarobaini.

Pendekezo kwa wakulima kuhusu utayarishaji wa viuatilifu vya mwarobaini: Nchini Ghana, Afrika, dondoo ya mbegu ya mwarobaini ilijaribiwa kwenye kabichi katika mafunzo ya Wakulima na ilikuwa na athari nzuri sana ya kuzuia nondo ya diamondback (Plutella xylostella). Hiki ndicho kichocheo chao: Ponda 30 g ya mbegu za mwarobaini (hiyo ni mbegu ambayo koti lake la mbegu limeondolewa) na uchanganye katika lita 1 ya maji. Wacha usiku kucha. Asubuhi iliyofuata, chuja suluhisho kupitia kitambaa laini na uitumie mara moja kwa kunyunyizia dawa. Haipaswi kuwa diluted zaidi.

Keki ya mwarobaini (mbegu ya mwarobaini iliyosagwa au unga wa mwarobaini) pia ina uwezo mkubwa kama mbolea na wakati huo huo itazuia mashambulizi ya nematode kwenye mizizi ya mazao (k.m. nyanya). Weka keki ya mwarobaini kwenye shimo la kupandia (200g kwa kila m2) na uchanganye na mkatetaka. Keki ya mwarobaini itafukuza na hata kuua viwavi na wadudu wengine wa mizizi. Dawa za kuua wadudu (azadirachtin) zitahamishwa hadi sehemu za juu za ardhi za mmea na kusaidia kuondoa wadudu huko.

 

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.

TEXT kwenye picha:

• A. Kiganja cha mbegu ziwe unga mbichi au ponda kilo 2 za majani. Kufanya umakini.

• B. Watie kwa dakika 25 kwenye maji ya moto au usiku kucha kwenye maji baridi.

• C. Kufanya kazi chini ya kivuli chuja mkusanyiko kwenye tanki iliyojaa nusu.

Koroga poda kidogo ya sabuni na ujaze tanki na maji safi ya baridi.

• D. Nyunyiza mimea majira ya alasiri kwa sababu mwarobaini kukatika kwenye mwanga wa jua.

KIELELEZO 8-13 - MAANDALIZI YA SULUHISHO LA NEEM