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.