Utangulizi
Nyanya ni zao la chakula na biashara. Kilimo cha zao hili hufanyika majira yote
(masika na kiangazi), na faida hupatikana haraka na ni ya kuridhisha ikilinganishwa
na mazao mengine. Pamoja na umuhimu wa zao hili, wadudu waharibifu na
magonjwa huathiri uzalishaji na ubora wa matunda. Ili mkulima aweze kupata faida
na kuongeza pato la kaya yake ni vema kuzingatia udhibiti wa magonjwa na wadudu
wa zao hili. Kipeperushi hiki kinatoa maelezo ya udhibiti wa magonjwa na wadudu
muhimu ya zao la Nyanya.

MAGONJWA YA NYANYA
Bakajani chelewa (Late blight)
Ugonjwa huu huenenzwa na vimelea vya fangasi. Husababishwa na hali ya hewa hasa
ya unyevunyevu, na huenezwa na upepo. Majani, shina, matunda hushambuliwa.
Majani huwa na ukungu mweupe na kijivu, na baadaye hukauka. Matunda huwa na
mabaka ya kikahawia na baadaye kuoza. Mashina pia huwa na mabaka ya kikahawia.

Udhibiti

· Nyunyiza dawa ya kuzuia ukungu hasa wakati wa masika, Dawa
zinazopendekezwa ni Ridomil, Dithane 45, Bravo, Funguran, milraz.
· Fanya mzunguko wa mazao. Usipande nyanya sehemu moja kila msimu au
palipolimwa mazao jamii ya nyanya km viazi mviringo, bilinganya, aina zote
za pilipili na nyanya chungu.
· Tumia mbegu safi
· Panda aina za nyanya zinazovumilia ugomjwa
Bakajani tangulia (Early blight)
Huenezwa na vimelea vya fangasi. Husababishwa na kuenezwa na hali ya hewa
pamoja na mbegu zenye ugonjwa. Mabaka ya kahawia yenye mistari ya mviringo
huonekana kwenye majani na shina. Baka jeusi hutokea sehemu ya tunda
inayoshikana na kikonyo.

Udhibiti
· Nyunyiza dawa ya Kocide, Funguran
· Teketeza mabaka ya mazao baada ya kuvuna
· Tumia mbegu safi na bora
Mnyauko fusari (Fusarium wilt)
Huenezwa na mbegu zenye ugonjwa. Husambazwa na vimelea vya fungasi
vinavyoishi kwenye udongo.
Ugonjwa hujitokeza zaidi wakati wa kiangazi. Vimelea hushambulia sehemu au
mirija ya mmea ya kupitishia maji na chakula. Mmea hukosa maji na chakula na
hatimaye hunyauka. Shina la mmea likipasuliwa ndani huonekana rangi ya kikahawia.

Udhibiti
· Tumia mbegu safi na bora
· Tumia mzunguko wa mazao. Nyanya zisizungushwe na mazao jamii yake
· Teketeza masalia ya mimea
www.ariuyole.go.tz
· Choma kitalu cha nyanya kabla ya kusia mbegu
Mnyauko bacteria (Bacterial wilt)
Ugonjwa husababishwa na vimelea vya bacteria vinavyoishi kwenye udongo.
Huenezwa na kusambazwa na mbegu na udongo wenye vimelea. Mirija ya mimea ya
kupitishia maji na chakula hushambulia na mimea hunyauka ghafla. Mmea hukauka
na kufa.

Udhibiti
· Panda mbegu safi
· Panda nyanya sehemu ambayo haijawahi kupandwa viazi mviringo,
bilinganya au nyanya chungu
· Tumia mzunguko wa mazao
· Hakikisha mfereji wa maji ya kumwagilia hayapiti kwenye shamba lenye
historia ya ugonjwa huu.
· Choma kitalu cha nyanya kabla ya kusia mbegu
Mnyauko vetisili (Verticillum wilt)
Hakuna dawa inayozuia au kutibu ugonjwa huu kwa sasa. Ugonjwa husababishwa na
ukungu (fangasi) kwenye udongo. Ukungu huu huishi kwenye udongo kwa muda
mrefu bila kudhurika. Ugonjwa huongezeka ikiwa mizimizi ya nyanya
imeshambuliwa na minyo fundo; au kukiwepo na hali ya ubaridi au ukame. Ugonjwa
husababisha hasara kubwa. Ugonjwa hushambulia sehemu ya ndani ya shina na
kusababisha sehemu hiyo kuwa na rangi ya kijivu. Majani hugeuka njano na mimea
kunyauka na kufa.

Udhibiti
· Tumia mzunguko wa mazao usiopungua miaka mine
· Ondoa mabaki ya nyanya shambani
· Tumia mbegu bora na safi
Bakadoa (Bacterial spot)
Ugonjwa huu huenezwa na vimelea vya bacteria vinavyoishi kwenye mbegu, pia
kwenye hewa. Huenezwa kwa kasi sana wakati wa masika. Madoa ya rangi kahawia
huonekana kwenye majani na matunda.

Udhibiti
· Panda mbegu bora na safi
· Tumia mzunguko wa mazao
· Teketeza masalia ya mazao
· Nyunyizia dawa ya funguran, Kocide101, Cobox, Bravo
Makovu bakteria (Bacterial canker)
Ugonjwa huenezwa na vimelea vya bacteria vinavyoishi kwenye mbegu na hewani.
Hutokea zaidi wakati wa masika. Majani hukauka nchani na makovu yaliyodidimia
hutokea kwenye shina. Matunda huwa na makovu yenye rangi ya kahawia sehemu ya
katikati.

Udhibiti
· Tumia mbegu bora na safi
www.ariuyole.go.tz 2
· Teketeza masalia ya mazao
· Tumia mzunguko wa mazao
Rasta (Yellow leaf curl)
Ugonjwa huu husababishwa na virusi na huenezwa na nzi wadogo weupe. Hutokea
zaidi wakati wa kiangazi. Mimea hudumaa na majani yaliyoshambuliwa huwa na
rangi ya manjano na pengine rangi ya zambarau. Nyanya hupasuka.

Udhibiti
· Nyunyiza dawa za sumu za kuua wadudu (Selecron, Dursburn, Actelic)
· Ng’oa mimea yenye ugonjwa
· Tumia mzunguko wa mazao
· Weka shamba katika hali ya usafi
Batobato (Tomato mosaic virus)
Ugonjwa husababishwa na virusi na hueezwa na mbegu na kugusana. Majani huwa na
mchanganyiko wa rangi hasa kijani kibichi na kijani kilichofifia (majano). Majani
hujikunja na manjani machanga huwa na maumbile yasiyo kawaida. Ukifikisha jani
huwa linavinjikavunjika.

Udhibiti
· Tumia mbegu bora na safi
· Ng’oa mimea iliyoshambuliwa
· Teketeza masalia ya mazao
· Weka shamba katika hali ya usafi

WADUDU WAHARIBIFU
Viwavi Matunda (Fruit worm)
Viwavi hawa hutokana na wadudu nondo. Viwavi hutoboa matunda na kuacha
matundu na hatimaye matunda huoza. Hupunguza ubora wa matunda.

Udhibiti
Nyunyizia dawa ya kuua wadudu. Dawa hizo ni pamoja na Actelic 50EC, Selectron,
Dursbaan, Maji ya majani ya mwarobaini au utupa pia huua wadudu.
Utitiri wekundu (Red Spider mites)
Hawa ni wadudu wekundu, wadogo sana wanaoweka utando chini ya majani, hasa
wakati wa kiangazi. Wadudu hawa hufyonza utomvu kwenye majani na kusababisha
majani kukauka.

Udhibiti
· Nyunyizia dawa za sumu. Dawa hizo ni pamoja na Actellic, Selecron,
Dursbarn na Thionex
· Mwagilia maji mara kwa mara
· Weka shamba katika hali ya usafi
www.ariuyole.go.tz 3
Inzi weupe (White flies)
Hawa ni Inzi weupe wadogo sana. Hujitokeza sana wakati wa kiangazi. Hueneza
ugonjwa wa virusi ujulikanao kama Rasta.

Udhibiti
Nyunyizia dawa za sumu za kuulia wadudu kama Selecron, Actellic, Dursban na
thionex. Pia maji ya majani ya mwarobaini na utupa.
Vidukari au Wadudu mafuta (Aphids)
Ni wadudu wenye rangi nyeusi au kuijani au kahawia. Hukaa chini ya majani na
kufyonza utomvu kwenye majani machanga. Hudumaza mmea na kushindwa kuzaa
matunda

Udhibiti
Nyunyizia dawa za sumu za kuulia wadudu kama Rogor, Actellic, Selecron, Dursban
maji ya majani ya mwarobaini na utupa, maji ya pilipili.
Minyoo (Nematodes)
Ni minyoo midogomidogo ambayo hushambulia mizizi na kuweka vifundo. Mizizi
hushindwa kuchukua maji na chakula kwenye udongo. Mimea hudumaa na
kushindwa kuzaa

Udhibiti
· Tumia mzunguko wa mazao
· Choma udongo wa kitalu kabla ya kusia mbegu kwa kutumia karatasi la
plastiki jeusi na nishati ya jua
· Choma masalia ya mazao
Sota (Cutworms)
Hushambulia miche ya nyanya hasa baada ya kupandikizwa shambani. Wakati wa
mchana hujificha kwenye udongo na usiku hujitokeza na kukata miche kwenye shina
usawa wa udongo.

Udhibiti
· Nyunyiza dawa za kuua wadudu kwenye shina usawa wa udongo
· Hakikisha miche inapata maji ya kutosha.

Carrot Production

Carrots (Daucus carota) grow well in Saskatchewan's climate and soils. The taproot is the edible portion of the carrot; the foliage has no economic value.

Soil Conditions

Carrot harvester (Photo courtesy Gary Bishop, Atlantic Cool climate Crop Research Centre, Agriculture and Agri Food Canada)

Carrots favour well-drained, fine textured soils with good water-holding capacity. Sandy, loamy or muck-based soils are suitable for carrot production. A pH range of 5.5 to 8.0 is desirable. Carrot seedlings are very weak, and do not tolerate soil crusting. Seedbed preparation must eliminate clods as they interfere with uniform growth of the roots. Since the taproot is the edible portion of the plant, the field should be tilled to a 30 cm (12 inches) deep to ensure that root penetration is not restricted. Crusting of the soil surface will prevent the seedlings from emerging. For this reason, avoid clay soils.

Raised beds are very popular in carrot production as they help the soil warm up faster in the spring, promoting faster emergence. The soil tends to be very soft in the beds, which is crucial for weaker carrot seedlings.

Seed Treatment

Seed costs have increased over the last 10 years. One reason is the higher quality seed currently produced. It was once thought that a 50 per cent stand was good in carrot production, but better varieties and superior seed production practices now have increased that figure to 80 per cent or more. Due to the seed’s higher value, it is best to treat it with a fungicide, such as Thiram 75WP, to prevent seedling blight, damping off and seed decay.

Pelleting carrot seed to increase its size improves the accuracy of planting and the uniformity of the carrot stand. Consult your local seed representative to get more information on precision seeding and seed pelleting.

Varieties

There are four main types of carrots:

Nantes:

Nantes carrots and their characteristic hot dog shape 2001 Scott Vlaun Seeds of Change

This is a popular carrot with a sweet taste. Nantes carrots are almost cylindrical in shape, and round off at the end rather than tapering off. They have a small core and a larger outer cortex. Sugars accumulate in the cortex, giving Nantes their sweet taste. Nantes carrots do not store for very long. They mature in early to mid-summer, and are usually eaten fresh.

Imperator:

This carrot type is the most commonly grown carrot because of its high yields and long storage potential. Imperators are long and tapered. They are a late-maturing variety, and generally have a larger, more fibrous core; therefore they do not have the sweet taste of other carrot types.

Classic bunches of Imperator carrots Photo provided by the University of Florida.

Chantenay:

Shape-wise, Chantenays are intermediate between a Nantes and an Imperator. They are tapered like the Imperator, but the bottom rounds off somewhat like the Nantes. Chantenays are also sweet tasting like the Nantes.

Danvers:

Davers are medium-length carrots, conical in shape, and thicker than Imperators. The end of the root is tapered. Danvers varities are used in both the processing and commercial fresh market industries.

The University of Saskatchewan Plant Science Department has conducted carrot variety trials the last two decades. Following are some varieties that perform best in Saskatchewan:

Nantes: Bolero, Earlibird Nantes, Favor, Forto Selection, Mokum, Nantes Coreless, Nantes Half Long, Napa, Napoli, Narova, Presto, Sytan, Touchon
Danvers: Danvers 126, Danvers Half Long, Kamaran, Kuroda Improved, Royal Chantenay
Imperator Nantes: Kamaran, Primecut
Imperator: Apache, A-Plus, Artist, Blaze, Carobest, Choctaw, Convert, Crusader, Eagle, First Class, Heritage, Nandrin, Spartan Premium 80

Seeding

Carrots should be planted early to mid-May in Saskatchewan. Seeding rates will depend on carrot type, the variety and the root size desired. General seeding rates are: 10 to 16 plants per 30 cm (12 inches) of row for Nantes varieties; and 12 to 18 plants per 30 cm (12 inches) of row for Imperator varieties. Higher carrot densities will give a higher total yield, but decreases average carrot size.

Row spacing can vary depending on equipment and planting practices. If planting in raised beds, the beds should be at least four inches off the ground on 51 to 102 cm (20 to 40 inch) centres. If planting in rows, inter-row spacing ranges from 41 to 76 cm (16 to 30 inches). Inter-row space is also dependant upon the row space capabilities of your tillage equipment and carrot harvester.

Carrot seed is small, and should be planted 1.9 to 2.5 cm (¾ inch to one inch) deep. Planting any deeper will slow emergence. Stanhay-type belt seeders are the most popular for carrots. Belts punched specifically to match seed size and desired spacing are available.

Fertility

Always base your fertilizer program on a soil test. Random soil samples should be collected from the entire field that you intend to plant. Due to climatic conditions, differing cultural practices, varying soil conditions and other situations, the crop’s response to the fertility program may vary from region to region.

Carrots will require 80 kg/ha (71 lbs/ac) of nitrogen on muck soils, and 110 kg/ha (98 lbs/ac) of nitrogen on mineral soils. Phosphorus and potassium will be required in 120 kg/ha and 250 kg/ha (107 lbs/ac and 223 lbs/ac) amounts respectively. Always base your fertilizer rates on a soil test.

Over-application of nitrogen can lead to excess top-growth, which will slow the growth and development of the edible taproot.

Irrigation

Adequate amounts and proper timing of water are critical in carrot production. Carrots do not respond well to lack of water, particularly in high temperatures. Moisture is crucial for germination and root development. Watering at germination will also help to prevent soil crusting, which retards the growth of a new seedling.

For the bulk of the growing season, carrots require approximately 2.5 cm (1 inch) of water per week. Lack of water or inconsistent watering will lead to woody flavoured carrots and irregular growth patterns or misshapen roots.

Harvesting

Harvest occurs when carrots reach an adequate size. However, sweetness and storage potential increase with maturity. Avoid wounding carrots during harvest to reduce the incidence of sclerotinia in storage. Carrots are harvested either by cutting off the tops, called topping and using a digger to lift the carrots, or by using a machine to pull out the carrots by the tops, and then topping them in the field.

Topping usually occurs in the field, when most of the foliage is chopped off, with only 2.5 cm to 5 cm (1 to 2 inches) of stem remaining. The rest of the stem is usually trimmed off prior to packaging.

Cooler soil temperatures during harvest will reduce the amount of field heat that needs to be removed from the carrots when in storage. Avoid drying out the carrots between harvest and in storage.

Carrots do well in cooler weather, but they do not withstand freezing temperatures. Carrots, if frozen, will have ice crystals on the outside of the root. Allow the carrot to thaw before attempting to harvest. Symptoms of excessive freezing are: splitting of the root, water-soaked appearance, flabby or a watery breakdown. Discard any carrots that exhibit these symptoms.

Storage

Carrots should have their field heat removed as soon as possible after harvest. If possible, harvest the crop close to 0°C (32°F). Once in storage, the crop should be kept at 0°C (32°F) and 100 percent relative humidity to ensure minimal moisture loss. State of the art storages can store the product for six to nine months, while conventional storages can maintain quality product for four to five months.

Carrots should be cleaned and washed when they enter the storage. During the wash process, any damaged or diseased carrots should be discarded. Prior to harvest, a two percent solution of copper sulphate should be used to clean the storage and kill any disease organisms that may be present. All contact surfaces should be dry before any product is stored.

Grades

The following are some of the requirements of carrots to be a Canada No. 1 grade:

A minimum length of 114.5 mm (4.5 inches)
A minimum diameter of 1.9 cm (.75 inches) in all cases (this depends on whether the package specifies a minimum and maximum diameter)
Carrots cannot be soft, flabby or woody
Carrots cannot be misshapen
Carrots must be “reasonably clean”, which means that they are practically free from caked dirt, mould or decaying matter and does not have more than 15 percent of the surface covered or stained.
Carrots must be properly trimmed. They cannot be trimmed into the crown, the length of the crown does not exceed one inch and the length of 75 percent of the tops can not be more than one-half inch

* The following grades were supplied by the Canadian Food Inspection Agency (CFIA). For a complete listing of all carrot grade standards, contact your local CFIA representative.

Pest Problems

Aster leafhopper phot by M. Herbut, ARC

Diseases

Aster Yellows – is caused by a phytoplasma (virus-like disease) spread by the aster leafhopper (Macrosteles quadrilineatus). Not all aster leafhoppers carry the pathogen. Do not plant carrots near fields planted to forage legumes or weedy areas where leafhoppers may be found. Many perennial crop hosts including medicinal species such as Echinacea are potential hosts for aster yellows. Symptoms of aster yellows include a witches’-broom appearance to the foliage, the growth of lateral, hairy roots from the taproot, and a yellowing and then bronzing of the foliage. Aster yellows are difficult to control because the cost of the insecticide is often greater than the economic damage incurred. A constant influx of aster leafhoppers will lead to the need for continued applications of insecticides.

Sclerotinia – caused bySclerotinia sclertiorum is a very significant disease in both the field and storage. Symptoms include foliage that is dark brown and coated with a whitish mould. Later on, black dots (sclerotia) will appear amid the white mould (mycelium). Infected carrots become soft and watery in storage. White mould covers the infected carrot, and the black sclerotia will follow. Control of sclerotinia begins with crop rotation and careful handling as carrots are harvested and put into storage. The storage units should be disinfected with a two per cent solution of copper sulphate. Avoid crop rotations with crops susceptible to sclerotinia, which include most all vegetable crops except sweet corn. Sclerotinia can persist in the soil for three to five years, therefore it is best to rotate with cereals and forages to break the disease cycle.

Insects

Asterleafhopper – see above

Pages

Wednesday, February 18, 2015

KILIMO BORA CHA NYANYA- MAGONJWA NA WADUDU