19. Recent techniques and strategies for improvement of old cashew plantations
In India over 60 percent of the planted area is covered under old plantations with age of the crop exceeding twenty years which contributes only 30 per cent of the total yield in the country. If these old plantations are improved through latest agro techniques the yield can be increased two folds. This can be achieved within a short span of five years.The ways and means of improving the production and productivity levels of the existing old cashew plantations particularly those raised with seedling progenies are discussed here below.In cashew plantations raised with seedling progenies, without initial training and pruning the plants shade each other. The research results have indicated that simple removal of dead wood, criss cross branches and water shoots allows better penetration of light and this has doubled the yield. Therefore this operation could be taken up to revive the oldand neglected plantations. The branches touching the ground may also be removed to facilitate easy cultural operations and nut collection.Criss cross branches should be headed back so that the canopy of onetree does not interfere with that of the neighbouring tree. The pruningwounds must be treated with bordeaux mixture paste (10 per cent). Itshould be done during April-May after the harvesting of the crop.
20.Consolidation of plantations by gap filling / replanting
Most of the old plantations have only 50 per cent plant population,as a result of mortality of trees due to CSRB infestation and othercauses. Through gap filling with high yielding clones, these plantationscould be consolidated and the productivity also could be increased.Gap filling could be also done with compatible tree crops mentionedearlier.
21. Rejuvenation of old trees by pruning
The normal optimum spacing recommended for cashew is8 m x 8 m. There is overlapping of canopy, in 10 to 15 years of agedepending on the variety unless the canopy is maintained by trimmingand thinning. Plantations which have overlapping branches will lead todead wood development and decline in yield in the later years. Suchplantations can be rejuvenated through canopy redevelopment by limbpruning.
1The re-development of canopy is done by beheading all the exhaustedbranches at 1.0-2.5 m height (Fig. 35). Immediately after beheading thetrees, the pruned wood needs to be removed from the plot so as toprevent the damage by shot hole borers as well as CSRB. Remainingportion of the trunk and exposed part of roots is swabbed with neem oilat least 2-3 times after beheading till new canopy is developed. Regularchecking for the damage by CSRB is to be done and managed. Thecut ends of the branches should be smeared with 10 per cent bordeauxpaste to prevent gummosis and entry of any other pathogens. Furthertying straw to the cut ends keeps the branches cool during summer.The best season for limb pruning is May-June i.e., immediately afterthe harvest of the crop.
The new flushes arise from the dormant buds on the trunk. Thesesprouts form the canopy within a period of 6-7 months depending onthe variety. Yield level during the first season after pruning is slightlylower while, from second season onwards it has shown to be betterthan the unpruned plants. The cashew trees after rejuvenation eitherby beheading or top working are more prone to CSRB. The old cashewplantations can be rejuvenated as explained above, provided they aremanaged well by taking care of individual plants to prevent damage byCSRB.
Good phytosanitation procedures are to be adopted to manage therejuvenated plants. The newly developed canopy needs to be protectedfrom TMB and leaf beetles as they are also more vulnerable for thedamage in the initial 5-6 months of canopy development. Care shouldbe taken to treat the cut wounds with 10 per cent bordeaux paste duringthe beginning of monsoon season to prevent any fungal infection andgummosis. If properly protected, the canopy redevelopment can help inenhancing the nut yield to the fullest potential of the plant after 2-3years (Fig. 36). In subsequent years the limb pruned trees should bepruned or trimmed as and when required. It may be noted that yieldlevels of limb pruned trees are much better than the freshly plantedcashew grafts of comparable years due to better root system. Pruningoperation should be taken up only after complete picking of nuts whichcoincides with temporary quiescent stage in cashew (May-June in westcoast of India).
21.1. Rejuvenation by top workingRejuvenation of old, unthrifty cashew trees by top working andgrafting with scions of better variety was developed in early eighties atAgricultural Research Station, Ullal, under University of AgriculturalSciences, Bangalore and subsequently modified as per local requirementand popularized by NRCC and several other cashew research centresin India
Though the top working is a promising technology to rejuvenate theold plantations of seedling progeny in a short period, the technologycould not be adopted on a large scale due to the problem of CSRBwhich damages and kills the top worked trees. The technology is beingrecommended only for the home-stead gardens of medium age whichcan be properly monitored and maintained.
21.2. Conditions and Points to be considered before top working:
1) Age of the tree: Tree should be within 15-20 years of age. Asfar as possible it should have smooth bark and should nothave many crevices in the bark at collar region. The colour ofthe trunk should be brown or grey and not black.2) No CSRB damage: The trunk as well as exposed root portionon the ground should be free from CSRB damage.3) Healthy Tree: Trees should be healthy enough with lowerspreading branches. It should have a well developed rootsystem and should have capacity to cope up with the growthof the new canopy. It should be free from other pests anddiseases.
21.3. Method of top working:
After the selection of the tree, top working involves two steps (i)beheading of the tree and (ii) grafting with an elite material on the newflushes emerging out on the beheaded stumps.
21.3.1. Beheading of the tree:br>The most suitable time for beheading the tree is April-May in WestCoast region. i.e. immediately after the harvest of the crop. It alsodepends on the fruit-bearing pattern of the tree (early, mid and lateseason) depending on varieties. After selecting the tree for beheading,the limbs should be cut and weight of the crown is reduced finally toretain the stumps of plants at 1-1.5 m height. While pruning the limbs,care should be taken to see that the bark should not be peeled or splitor damaged in the retained stump. Immediately after the beheading ofthe tree, wounds should be treated with 10 per cent bordeaux paste sothat there should not be any gummosis and fungal infection in the wound.After beheading, the cut plant material should be cleared from the siteimmediately to prevent the harbouring of pathogens and insect pests.
Grafting of new flushes emerging from the trunk of the cut tree canbe taken up after 45 to 60 days. About 200-300 shoots emerge from thetrunk below the cut end depending on the size of the remaining trunk(Fig. 39).About 15-20 shoots of different branches in different directionsmay be selected and softwood grafting technique (Fig. 40) may betaken up with the scion material of required elite varieties. The periodbetween June to August is most suitable for top working in west coastregion. After successful grafting, remaining ungrafted shoots need tobe gradually removed in a phased manner. About 4-5 months later, only10-12 successful grafts in different branches at different directions maybe retained and rest may be removed. The new flushes emerging fromthe trunk subsequently should also be regularly removed. Initially graftsor shoots may be protected from damage by wind and animal by stakingand support with sticks. From second year of grafting, the plant willgrow into a tree and give flowers and fruits like a normal tree.
21.4. Pest management in the rejuvenated trees:
The trees which have been top worked need to be checked for anysymptoms of CSRB pest incidence right from the first week of topworking at 15 days intervals. Normally the fork regions and the cutends (if uncovered) will have the pest entry. It is identified by exudationof the fine frass material in small quantity in the infested region. Thesespots on the bark should be chiselled cautiously, without making anydamage to the bark of the top worked trees. The tunnel made by thegrubs, which bore into the bark, can be traced out by the freshness offrass. The young grubs remaining inside need to be removed and killed.In case the frass comes out from the root zone then the soil at thatspot needs to be dug out and the infested root should be checked forthe grubs which are normally found on the underside (ventral portion) ofthe roots.The chiselled surface needs to be treated with either neem oil orbordeaux mixture as explained earlier. Repeated infestation of treatedtop worked trees is not uncommon. Hence constant vigil of these treesand those immediately next to it is of utmost importance during themonths of July to November when the symptoms of infestation likefrass and yellowing of the shoots is noticed.
Only the fallen nuts should be collected from the base of the tree toavoid damaging the flowers and unripe nuts (Fig. 41). The fruits shouldnot be plucked from the tree. The nuts, after separating from the fruits,should be washed with water, sun dried for 2-3 days (Fig. 42) and storedin gunny bags at a height of atleast 4 inches above the ground byplacing it over a wooden plank. Nuts should be sold in the same yearand should not be stored for the future.
23. Nut yield
All the varieties recommended have a yield potential of over 8 kgper tree or 1 to 1.5 tonnes per hectare. Though cashew yield startsfrom the fourth year, its full potential (about 8 kg per tree) will be realizedafter 8-10 years depending on the level of management (Fig. 43) .
24. Cost and returns
The cost and returns of cashew grown on a hectare of the land inIndia is shown in the tables 3 - 6. The returns from inter or mixedcropping is not taken into consideration. Cashew as a single crop blockhas been taken into account. From this table, one can analyse thecost and returns from cashew alone in different phases of growth. In thefirst year, the cost involved per tree is Rs. 101, but over the years onecan notice a decrease in it. Cashew starts yielding from the fourth year.It goes on increasing from one kilo in fourth year to 7 kilos in tenth year.The economical return starts from the fifth year, where it isaround Rs. 2,300 per ha. and at the end of the tenth year it will bearound Rs. 29,000 per ha. But, if one takes the cumulative returns forthe ten years, it will be Rs.59,700 per ha (or Rs. 383 per tree). Bygrowing the inter crop, returns can be expected in the very first year ofplanting. The economical sustainability could be achieved by inter andmixed cropping even during the time of fluctuations in prices of themain crop.
24. Cost and returns
Cost of cultivation per hectare of cashew
Spacing: 8 m x 8 m (156 plants)
Table 3: From 1st to 3rd year
25. Significance of organic cultivation and its potentiality
Cashew is grown in most of the places as a naturally grown cropwith less attention and it has not confined to any practices of applicationof inorganic or organic inputs. Hence the expected returns are notachieved, the major reason being the organic waste recycling is notproperly dealt with. Leaf litter, dried twigs, branches, fruits etc. shouldbe utilised as organic inputs for cashew. There is growing demand fororganic food grains, fruits, vegetables and other products which wouldfetch premium price in the international market. Since dairying andrearing of animals are a part and parcel of most of the farming systems,the availability of organic materials in plenty determines the scope fororganic cultivation of most of the crops, apart from converting a largenumber of smaller cashew holdings into organic.In organic farming, most important aspect is maintaining the soilfertility status. When organic materials are added to the soil, the soilmicrobes work on them and convert them into readily available nutrientsfor the plants besides improving the soil structure. Earthworms,millipedes, centipedes and many more soil macro fauna also play majorrole in improving the properties of soil.
Annexure - 1
Organic sprays which could be utilised in cashew
1. Sprays providing nutrition and imparting protection frominsects/ dise.asesa.
Cattle urine: For every litre of cattle urine, 8-10 litres of wateris added and sprayed.
b. Compost tea:
One kg of well degraded compost powder ismixed in 40 litres of water, filtered and sprayed. Varanashi Biospray is one such formulation which is readily available in themarket.
10 kg fresh cow dung, 5-10 litres of cattle urine,2 kg of black Jaggary (or palm sugar), 1 kg legume seed powder(black gram/ bengal gram/ green gram), one handful soil fromthe bunds of the field and 200 litres water. All these constituentsare mixed in a barrel, kept in shade for 2 days stirring threetimes a day. The mouth of the barrel should be kept closed witha wet gunny bag. The solution is to be used for spraying within7 days of its preparation. Filter before use.
d. Beejamrutha :
5 kg fresh cow dung, 5 litres cattle urine, 50 gCaO (lime), one handful of soil from the bunds of field and20 litre water. All these constituents have to be thoroughlymixed and the mixture could be used for the seed treatment.Treated seeds have to be shade dried and sown. The treatmentenhances germination. Cashew nuts can be soaked for a dayin this solution before sowing.
2. Organic sprays for control of pests.
a. Strychnos nux-vomica L: Seeds, bark, leaves and roots ofthis plant are used. Two kg of the plant part is crushed andboiled in 30 litres of water. The solution should be filtered andsprayed in 1 : 2 proportion with water. It is useful in avoidingTMB to certain extent. Spraying once in 15 days during theflushing period is suggested.
b. Neem seed concoction: One kg of pounded neem seeds aresoaked in 10 litres of water for 10-12 h and 20 litres of water
with 1 ml of liquid soap are added, filtered and sprayed. It isuseful against some insect pests.
c. Tobacco concoction:
200 g tobacco should be tied in a pieceof cloth and boiled in 2 litres of water and allowed to soak for24h and filtered. 100 ml of neem oil with 20 ml of liquid soap areadded and diluted in 5 litres of water and sprayed.
d. Neem oil/ Castor oil: 200 ml of neem / castor oil is mixed with40 ml of liquid soap and diluted in 10 litres water and sprayed.This is effective against TMB if sprayed frequently.
e. Lantana: One kg lantana (Lantana camera L.) leaves are finelycrushed and diluted in 10 litres of water and sprayed. Effectiveagainst leaf miner.
f.Fish:One kg of fresh fish is crushed and mixed with one kg ofblack jaggary or palm sugar and allowed to ferment for 15 days.This preparation may be used at 15 ml per litre of water forspraying. This is effective against bacterial diseases.
g. Annona (Custard apple- Annona squamosa L.) + Chilli +Neem seed: Two kg of Annona leaves should be shredded andmade into paste by adding some water. 500 g of dry chillieshave to be soaked for 8-10 h in water. Neem seed should bepowdered and soaked for 8-10 h in water. All the ingredients aremixed and water is added to prepare a solution. Then diluted to50 litres with water and sprayed, controls thrips and caterpillars.
h. Chilly + Garlic: One kg of green chilly along with 3 garlic bulbsis crushed to make a paste and soaked in five litres of water for8-10 h. This solution is dissolved in 18 litres water and sprayed.Effective against leaf hoppers and grass hoppers.
Note: All the sprays are to be carried out during either morning orevening hours.Before the arrival of chemical pesticides, there were several traditionalmethods of insect and disease control, which slowly disappeared. Offlate, they are gaining importance once again. Such organic controlmeasures have been collected from various sources and listed here forthe benefit of the organic farmers. Some of them have been tried incashew cultivation. Hence farmers are suggested to try appropriatecombinations on a small scale and extend the successful results toother plants in the orchard.
Farmers are requested to report success or failure to the authorsso as to make suitable changes in next editions.
2.1. Some of the organic pesticides being used in Cambodiawhich could be utilised to control Tea Mosquito Bug (TMB)menace in cashew
Cambodian farmers are using organic pesticides made in the farm.Touch Visalsok and Edwin de Korte have documented a good numberof such preparations. Some of these are reported to be useful againstinsects similar in feeding habits as that of TMB. Three such preparationshave been detailed here below. The quantity of ingredients and the timeof spraying should be standardised according to local requirementsafter proper experimentation.
Chop all the pesticidal plants into 5 litres of water in a jar. Cattle urine (2 litres) is added into the jar every day. The jar is closed and placed under the tree shade. The mixture has to be stirred daily and allowed to stand for 15 days until a clear and yellow solution is observed. The extract of the above mixture is diluted with water to 1 : 20 ratio and is applied at morning or evening hours.
Pound the above ingredients and mix with 5 litres of cattle urine.The mixture is kept for a week. It is filtered and the filtrate is mixed with20 litres of water before applying onto the infected plants. It isrecommended to be sprayed once in a week
The above ingredients are cut into small pieces and added to a jar containing 20 litres water and 5 litres of cattle urine and allowed to ferment for a week. The extract is diluted in water at 1:15 ratio before use and it should be applied with an interval of 2-3 days.
3. The preparation of Bordeaux Mixture which is used to alimited extent in organic cultivation
One kg lime (CaO) should be dissolved in 5 litres of hot water anda solution is prepared. One kg copper sulphate (CuSO4) crystals aretied in a cloth and suspended in 5 litres of water in another vessel.When both the solutions are ready, lime solution should be added slowlyto the copper sulphate solution by stirring to get 10 litres of thick solution.This is 10 per cent bordeaux paste. If diluted further by adding additional90 litres water to make the volume to 100 litres results in one per centbordeaux solution, which is useful for spraying cashew nurseries inrainy season. The bordeaux paste is used to smear the cut surface ofcashew trees.
Annexure - 2
Organic inputs and their conditions of use
To market products with organic label, it has to be certified byappropriate certification agency. There are several certifying agenciesin India. The names and address of the recognised certifying agenciesoperating in India is listed in APEDA website (Annexure-5). A Few areinternationally recognized.The organic inputs which could be used in a certified organic farmis listed in the tables below. Organic wastes available in certifiedplantations are permitted to be used as inputs in organic cultivation.Certain other products are allowed for use in organic agriculture for thecontrol of pests and diseases (plant protection). Such products shouldonly be used in absolute necessity and should be chosen after takingthe environmental impact into consideration.Many of these products are restricted for use in organic production.In the table “restricted” means that the conditions and the procedure foruse shall be set by the certification programme.
1. Substances of plant and animal origin
The procedure for getting organic certification is quite complex. To obtain the certificate, the organic growers should maintain necessary documents and follow strict guidelines and have to undergo periodical inspections from the certifying agencies. In a way it makes the farmers disciplined and handle their produce as per the international standard.If there is no assured market with premium price, certification is of no value. This requires a lot of patience and hard work. The main objective of this book is to make the farmers take up organic and sustainable agriculture. Regarding organic certification only introduction is given in this book and there are still a lot of things left uncovered.