SUMMER CROPS (MAIZE, SOYA BEANS, SUGAR BEANS, SMALL GRAINS, GROUNDNUTS)

Fertilizers & Herbicides

  • When soil sampling, how does one take a soil sample? Can lime be applied at planting?
    - When taking a soil sample, it must be done in a manner that largely represents the field to be planted. If a field has got different types of soils or the same soil type but has different crops, take the soil samples separately. Random sampling, Z-scheme or the M scheme are some of the methods that can be used when taking a soil sample. The best method is random sampling, avoid sampling in areas where fertilizers are normally staked, in the field, storm drains, termite mounds and any unsightly areas of the field being sampled.
    - Depending on the crop, Lime application should be done well before planting, in most cases at least 3months before planting. In potatoes lime should never be applied prior to establishment rather apply the lime at some point in the rotation.

 

  • How many bags of basal fertilizer should l use per hectare?
    - The number of bags to be used per hectare is largely determined by soil analysis results, yield target, cropping history, area potential and variety of crop involved.

 

  • If we fail to apply Compound D at planting, can we apply Compound X in maize at 4 to 5 weeks after emergence?
    - This will be difficult, farmers are encouraged to always use a recommended basal fertilizer at planting. This is because phosphate is immobile in the soil and as such the crop will not benefit from side dress applications involving phosphate once the crop is established without this nutrient.

 

  • How much gypsum can we apply in groundnuts per ha, at what stage of the crop?
    - The quantity ranges from 250kg-400kgs/ha, this is applied on top of the crop from the onset of flowering, split apply for long maturing groundnut varieties.

 

  • Which pre-emergence herbicides should l use for (shamva grass, couch grass, nutsedge, broadleaves e.t.c)?
    - Prowl can be used pre-emergent for shamva grass control in the following crops, cotton, maize, soya
    - There is no pre-emergent herbicide for couch grass, however for established couch with intact rhizomes glyphosate can be applied to clear the couch grass before planting(therefore post emergent control of couch grass is possible with glyphosate in non crop situations). Rates of 4lt/ha and above are recommended.
    - The only pre-emergent herbicide available for nutsedge is Authority 480SC registered for use in Soyabeans and Tobacco. However in all other cases, suppression is possible with the chloroacetanilide groups, i.e, Lasso, Dual Magnum, Frontier Optima, Acetochlor etc.
    - The choice of herbicides is influenced by a number of factors, the most important factor is the type of weeds to be controlled as this allows the herbicide to be matched to the weed spectrum, other factors include, the crop involved, rotational considerations, cost, ease of application, crop stage, size of weeds etc.

 

  • Is moisture important when applying pre-emergence & post emergence herbicides?
    - Moisture is critical for pre-emergent herbicides as it activates the herbicide for it to be effective. Prolonged dry spells after application of pre-emergent herbicides will result in reduced effectiveness, in such cases lightly incorporate the herbicide using for example spike-toothed harrows.
    - Moisture is not required for most post-emergent herbicides, the most important factor is the presence of the target weeds and these should be actively growing at the time of application. It is important to note that rainfall or irrigation after application of most these herbicides can reduce their effectiveness.

 

Insecticides & Fungicides

  • Which one is the best product for stalk borer control?
    - Most products registered for stalk borer control in Zimbabwe are effective but the choice of the chemical depends on the farmer’s choice on ease of application and affordability.

 

  • When should we spray for bean stem maggot in sugar beans?
    - Bean stem maggot is sprayed against on stipulated intervals, thus day 3, 6, 13 and 20 after the emergence of the bean crop. The most effective way however is to seed dress with  Apron star before planting.

 

  • How do we control soya bean rust & at what stage?
    - Soya bean rust can be controlled by spraying a number of recommended fungicides from day 50-70 after crop emergence. Normally spray from the onset of flowering.

 

  • How can we control maize streak virus?
    - When planting maize out of season Maize Streak Virus is the biggest challenge, always seed dress with Gaucho or Cruiser. The products will help control leaf hoppers which are the main vectors of the virus in maize. Incidence of MSV is very high in areas where irrigated pastures and or wheat are grown. A number of new varieties with improved tolerance to MSV are coming into the market. It is best to check with your seed supplier.

 

  • Which product is best for termite control in maize?
    - Regent and Imidachloprid 200SL/350SC are registered for control of termites in maize. The two products are applied prior to termite attacks, Regent is applied at planting and can be combined with most pre-emergent herbicides while Imidachloprid is applied 8-10 weeks after crop emergence prior to termite attacks.

 

  • How can one control witch weed in maize?
    - Witchweed(Striga spp.) chemical control using herbicides is very difficult in maize. By nature, witchweed is parasitic, i.e. it attaches itself to the host plant through a structure called haustorium and begins to draw nutrients from the affected maize plant, most of this damage occurs before the witchweed emerges above the ground. Thus makes it difficult for most herbicides to control the weed during this stage. While it emerges above the ground later and products such Stella star can be used, this is usually too late for effective results. Management of this problem involves the combined use of cultural practices, rotate with legume crops e.g cowpeas and or apply manure, optimal nitrogen fertilization can also help.

 

  • Which grain protectant can effectively control storage insects like LGB?
    - Actellic gold Dust exclusively distributed by ZFC limited, it is available in most retail outlets.

 

 

HORTICULTURE CROPS

Fertilizers & Herbicides

  • Which crops can be grown throughout the year & which ones are sensitive to frost?
    - Most crops broadly fall into two categories, that is the warm season crops and cool season crops. Most warm season crops will not do well in winter and most of them succumb to frost injury making it difficult for winter production e.g, maize tomatoes, pepper etc

 

  • Which fertilizers are the best for horticulture crops (Potato, Brassicas, Cucurbits and Tomatoes)?
    - ZFC has got a wide range of fertilizers, for the basal fertilizers, one can use Vegetable blend (9:24:20), Compound C (5:15:12), Compound S (7:21:8) and for the top dressing fertilizers apply Ammonium Nitrate, Potassium Nitrate, SOP/MOP, Calcium Nitrate, Potato super  top (23:0:24). The importance of trace elements in horticulture cannot be overemphasized and ZFC manufactures the following speciality fertilizers for the supply of trace elements, Quick start plus, Quick grow plus, Best bloom plus, Foliar 15 and Foliar feed for use in horticultural crops.

 

  • Do foliar fertilizers improve quality & yield of horticulture crops?
    - Foliar fertilizers improve the quality of horticultural crops as they supply the necessary trace elements which neither the soil nor the main fertilizer program can adequately supply. The yield aspect is largely driven by the effective use of  the basal and top dressing fertilizers to meet the nutrient guideline per crop as well as other aspects of crop management.

 

  • Which herbicides can be used in horticulture?
    - Very few herbicides are registered for use in horticulture, herbicides such as Lasso, Dual, Goal, Fusilade, Paraquat and Glyphosate(Round Up) are frequently used however. It is important to ensure the product is registered in the particular crop for which one intends to use it otherwise serious crop damage occurs.

 

  • Can Compound D/ Maizefert be used in crops like tomatoes?
    - Compound D (Maizefert) should not be used in tomatoes because they contain a marked percentage of Chlorine which tends to hamper the growth of tomatoes resulting in low yields.

 

  • When is the best time to apply basal fertilizers?
    - The best time to apply basal fertilizers is always before or at planting.

 

Insecticides & Growth Regulators

  • Which cost effective nematicides can we use in Solanaceous crops like tomatoes & potatoes?
    - Depending on the unit area to be covered, non fumigants such as Solvigo and Fenamiphos are cost effective while Basamid or Metham sodium can be used as fumigants.

 

  • What can be used for cutworm control in most horticulture crops?
    - To control cutworms, one can drench or spray Lambda cyhalothrin, Chlopyriphos and Fenvalerate, Decis forte, Carbaryl onto the base of the horticultural crops. This treatment should be done within a week after either transplanting or emergence of the crops.

 

  • Does Rhizobium replace basal fertilizers in sugar beans & soya beans?
    - Rhizobium inoculation helps the plant fix nitrogen with the result that for the nitrogen requirement very little or no nitrogen top dressing fertilisers are required. Basal fertiliser is still required in all cases.

 

  • Which are the common insect problems for specific horticulture crops, how do we manage them? (e.g. red spider mite in tomatoes, tuber moth in potatoes, DBM in brassicas, fruit fly in cucurbits)
    - Horticultural crops are susceptible to different insect pests. These pests range from their larval to their adult stages and these include the leaf miners, leaf hoppers, diamond back moth, aphids, red spider mite, white fly, thrips, tuber moth, bollworms, cutworms etc.

 

  • For how long can we spray the same insecticide in one field?
    - It is  advisable that farmers carry out scouting procedures for insects before a decision to spray any insecticide is made. The decision to spray should only be done when insects reach economic threshold levels. In most cases 2 or 3 sprays of a registered pesticide should applied before changing to another pesticide from a different chemical group. However always be guided by the label.

 

Fungicides

  • Can preventative fungicides (Copper Oxychloride, Dithane M 45, and Bravo) completely prevent fungal diseases from developing?
    - Fungicides can be classified into preventative and curative. It is important however that when an infection has taken place, curative fungicides be used to control the infection. A combination of both groups of fungicides is usually employed to avert crop losses.

 

  • My crops are wilting what can l use?
    - There are several causes for plants to wilt. However, it is critical that each case be diagnosed such that the most appropriate remedy is advised.
    - Which chemicals are best for powdery & downey mildew control in cucurbits?
    - The best chemicals to use for powdery mildew in cucurbits is Benomyl (Benlate), Folicur. Use Ridomil gold for Downey mildew.

 

  • My tomatoes are cracking, have deformed shapes or rolled leaves what can l use?
    - One of the reasons for the cracking of tomatoes could be inconsistencies in irrigation regimes. Rolled leaves could possibly be a viral infection, unfortunately it has no cure. Leaf roll can also be caused by environmental conditions mostly cold temperatures. The pattern should normally be used to diganose the environmental condition involved.

 

CASH CROPS

Tobacco Seedbeds

  • Which fertilizer is recommended and at what rates?
    - Tobacco Seedbedfert (7:21:8) can be used for tobacco seedbeds. The general recommendation for a 36 m2 seed bed ranges between 3 to 6 kg.

 

  • Is Calcium nitrate better than AN in top dressing tobacco seedbeds?
    - It is preferable to use calcium nitrate to top dress tobacco seedbeds as its use does not complicate hardening processes. It usually results in a  much quicker response than AN.

 

  • Which herbicides can be used in tobacco seedbeds?
    - The herbicides that can be used in tobacco seedbeds are Clomazone 4 EC (pre-emergent)-usually at sowing and Fusilade forte or Agil post emergence.

 

  • Which nematicides can be used in tobacco seedbeds, especially just before sowing?
    - Most nematicides are used at least 2 weeks in advance of seedbed establishment.

 

  • Which chemicals are replacing Acephate, Monocron and Methamidophos in the seedbeds?
    - Thunder, Decis forte, Confidor, Actara can be used in place of the phased out products.

 

  • How can leaf spots be managed in the seedbed?
    - Alternaria leaf spots can be managed by use of preventative fungicides such as Bravo, Copper, Mancozeb, Antracol. Bion can also be used for an activated response before infection.

 

Tobacco Lands

  • Blends over Compounds (Separation, efficacy & rates)
    - Choice will depend among other things cost and availability of trace elements in the fertiliser, but factors such as separation of blends should be considered if transporting the product over long distances.

 

  • What are the benefits of using gypsum in tobacco?
    - It improves quality by maintaining leaf integrity, resulting in a much stronger leaf with resistance to shattering, this results in very low levels of trash.

 

  • What rates of Ammonium Nitrate can be used in tobacco per ha?
    - Depends on a lot of factors, e.g soil type, residual fertiliser, amount of rainfall received etc, a 3.5te/ha crop normally requires 80units of Nitrogen supplied from both the Basal and Nitrogen top dressing. Usually 150-200kg/ha of AN will do.

 

  • What can we use to manage leaf spots in tobacco?
    Use Folicur, Score, Nativo, Amistar top to control Alternaria and Frog eye leaf spots in tobacco. Always use Bion at 5-7 and 8-9weeks in the lands.

 

  • Which suckercides are recommended in tobacco & at what rates?
    Sukerkil (N-Decanol)  4lt/100lt water and Accotab 1.5lt/100lt, Apply using either cup 8 or cup 12 per plant to cover all leaf axils without excess runoff into the soil. Always read the label first!