Rain deficit moisture stress management in Plantation crops

Oil Palm
Coconut, Cocoa and Arecanut
Cashew

Oil Palm

Oil Palm is a perennial crop and is mostly grown under irrigated conditions except Kerala and Mizoram. As the growth of oil palm is indeterminate in nature, the vegetative and reproductive stages are continuous and cannot be separated.

If monsoon is delayed by 15/30 days – In oil palm plantations, soil moisture can be conserved by mulching with leaves cut while harvesting fresh fruit bunches, male inflorescences and empty fruit bunches providing windbreaks, application of anti - transpirants/growth regulating chemicals and by removal of young inflorescences. In hilly terrains, mulching, formation of half moon terraces bench terraces, contour bunding and planting on the contour line, use of drip irrigation system and construction of water storage tank for irrigation could be followed for soil and water management.

Rain deficit at vegetative, reproductive and terminal drought – The quantity of water given to oil palm throughout the year by drip/micro - jet irrigation is strictly based on recommended schedule. The data relating to pan evaporation or Penman’s estimate of evaporation for a particular place is multiplied by a crop factor of 0.7 is taken into consideration for arriving at the correct irrigation schedule. In general, the water requirement of oil palm is scheduled viz., June – Sept.:100 - 150 litres/palm/day; Oct. – Feb.:160 - 170 l/palm/day; Mar. – April: 215 - 265 l/palm/day; May – June: 350 l/palm/day.

Coconut, Cocoa and Arecanut

1. If monsoon is delayed by 15 days

Crop	Contingency measures
Coconut	To avoiding nut dropping, irrigation needs to be continued. Prophylatic bud rot treatment by crown application of Bordeaux mixture 1.0% or Mancozeb 75 wp 5g/300 ml or phosphorus acid (Akomin) solution (0.5%) @ 300 ml/palm at bimonthly interval (First application may be completed before 15 th June). Removal of the stem bleeding affected portion & swabbing the wound with fungicide Hexaconazole 5EC (5.0 % solution) or application of a pas te of talc formulation of Trichoderma on the affected area. Adopt proper recommended prophylactic management measures for rhinoceros beetle and red palm weevil.
Arecanut	To avoiding nut dropping, scorching and necrosis, irrigation need to be continued. Prophylatic bud rot/ fruit rot treatment by crown application of Bordeaux mixture 1.0% or phosphorus acid (Akomin) solution (0.5%) @ 300 ml/palm at bimonthly interval (First application may be completed before 15 th June).
Cocoa	To control of tea mosquito bug in the event of infestation : Spray any one of following insecticide lambda cyhalothrin (0.003%) 5 EC 0.6 ml/ L or Imidacloprid 17.8 SC 0.25ml/ L. Repeat the spray 15 to 20 days after first spray if the infestation persist. To control mealy bug : Spray fenthion (0.04%) 80 EC 0.5 ml/ lit or dimethoate (0.06%) 30 EC 2 ml/lit. If reoccurrence of the pest is noticed, give second spray after an interval of 30 days.

2. If monsoon is delayed by 30 days

Crop	Contingency measures
Coconut	Irrigation need to be continued to avoid nut dropping leading to reduction in yield. Prophylatic bud rot treatment by crown application of Bordeaux mixture 1.0% or Mancozeb 75 wp 5g/300 ml or phosphorus acid (Akomin) solution (0.5%) @ 300 ml/palm at bimonthly interval (First application may be completed before 15 th June). Removal of the stem bleeding affected portion & swabbing the wound with fungicide Hexaconazole 5EC (5.0 % solution) or application of a paste of talc formulation of Trichoderma on the affected area. Gradient outbreaks of scale insects ( Aspidiotus destructor ) and slug caterpillars ( Macroplectra nararia / Conthyla rotunda ) and sporadic outbreaks of inflorescence caterpillar, Batrachedra arenosella may occur in endemic spots. Otherwise the aforesaid three pests are of minor pests infesting coconut.
Arecanut	Inflorescence die back (The disease is already prevailing in most of the areca growing areas) Removal and destruction of diseased dried bunches as a phytosanitory measure to reduce the inoculum. Spraying with zineb or mancozeb (0.2 %) at the time of opening of female flowers and one more spray after 40 - 45 days. Severity Spindle bug ( Carvalhoia arecae ) , red and white mite (Raoiella indica and Oligonychus indicus) and scale insect infestation may increase due to extended summer. To control spindle bug, spray spindle leaf and inner most leaves of palms in infested plantations with dimethoate (0.06%) 30 EC 2 ml/ lit of water. To control r ed and white mites, spray Kelthane 18 EC (0.036%) or dimethoate (0.06%) 30EC @ 2 ml/litre of water to the lower surface of leaves. Repeat spraying at an interval of 15 to 20 days if there is reoccurrence of pest. For scale insect: Spraying dimethaote (0.06%) 30EC 2 ml/litre of water to the tender bunches was found to be effective in containing scale insects.
Cocoa	Infestation of tea mosquito bug and mealy bug may flare up by delayed monsoon. Above mentioned control measures need to be adopted.

3. Rain deficit at vegetative phase

Crop	Contingency measures
Coconut	Life saving irrigation is needed for the pre-bearing coconut plants.
Arecanut	To control basal stem rot, root feeding with 100 ml of Hexaconazole (5.0% solution) at quarterly intervals and basin application of Trichoderma enriched neem cake @ 2 kg/palm (50g of T. viride talc formulation mixed with 2 kg neem cake at the time of application). Initial growth and establishment of arecanut seedlings will be affected due to incidence of red and white mites, scale insects. Recommended arecanut management measures mentioned above may be taken up.
Cocoa	Control measures for tea mosquito bug need to be continued. Cherelle rot can be controlled by spray with Carbendazim ( 0.05 %), or mancozeb 0.2%.

4. Rain deficit at reproductive stage

Crop	Contingency measures
Coconut	Prevent nut dropping and abortion of flowers irrigation is needed at least once in 15 – 30 days depending on the soil type. Though raised as a rain fed crop, coconut is sensitive to moisture stress during reproductive phase which is a continuous process. Incidence of coconut eripophyid mite, Aceria guerreronis could escalate in the event of continuous drought.
Arecanut	Incidence of scale insects may flare up in the event of continuous drought.
Cocoa	Cherelle rot can be controlled by spray with Carbendazim ( 0.05 %), or mancozeb 0.2 %. Infestation of tea mosquito bug a nd mealy bug on the pods may affect pod yield and quality. Above mentioned control measures need to be adopted.

5. Terminal drought

These crops cannot withstand drought for long as these are irrigated crops. Life saving irrigation is needed for survival of the plants.

Crop	Contingency measures
Coconut	The following activities may be taken up as part of cultivation practices to prevent the effects of deficit rain/moisture or excess rainfall. Above mentioned diseases like basal stem rot, stem bleeding and leaf blight may become severe and kill the palms. Fungicidal application for individual diseases need to be taken up to save the palm. Drought conditions/low rainfall conditions Mulching with coconut/arecanut leaves/coir pith Husk burial in interspaces – 1.5 m width and 1.0 m depth with 5 - 6 layers of husk Drip irrigation with fertigation Water harvesting structures recommended for the region
Arecanut and cocoa	The following activities may be taken up as part of cultivation practices to prevent the effects of deficit rain/moisture. Drought conditions/low rainfall conditions 1. Mulching 2. Drip irrigation with fertigation

Cashew

Majority of the cashew plantations established in India are under rainfed condition and very few only are under irrigation. The cashew adapted well in west and east coast regions and subsequently spread to hilly and plain regions of Karnataka. Tamil Nadu, Gujarat, Chhattisgarh, and NEH States. The cashew is suitable to diverse climatic conditions and rainfall pattern ranging from scanty rainfall region (around 800 mm) to heavy rainfall region (around 4000 mm) thus showing its wide adaptability.

If monsoon is delayed by 15 - 30 days - The cashew is planted after onset of monsoon from June to September. If there is delay in onset of monsoon, planting should also be delayed coinciding with monsoon. In fact, fresh grafts when planted require sufficient soil moisture for initial establishment and hence cashew is planted during monsoon season. Whenever there is drought situation after planting they need protective irrigation. The irrigation through pitcher (hold pots) is recommended in dry land situations.

Rain deficit at vegetative phase - Established plants survive even in adverse soil moisture conditions. If the drought situation persists due to low rainfalls in the rainy season, there is every possibility of yield getting affected. Under such situation to reduce the yield loss, one or two protective irrigation may be given wherever irrigation facilities exist. However, mulching of basin by dry biomass is helpful in conserving soil moisture.

Rain deficit at reproductive phase - Due to the non-uniform distribution of rainfall over the years, cashew experiences severe moisture stress particularly during reproductive phase from December to May, which adversely affects ins flowering and fruit set causing flower drying and immature nut drop. Under severe moisture stress situations drying of flowers, poor fruit set and nut development owing to field loss is observed. To overcome such problems, proper soil and water conservation measures like crescent bund, trenching, inward basin etc. coupled with coconut husk burial or mulching has been found useful.

Supplemental irrigation of 200 litres of water/plant once in 15 days during January to March from water collected in ponds through rain harvesting helps in flowering and nut development by improving the microclimate with increased humidity. It also leads to increased nut and kernel weight by reducing flower and nut drying to some extent. Drip irrigation during fruit development stages wherever water is available may be helpful during the drought situation to rainfed cashew crop. Normally for west coast of Dakshina Kannada irrigation by drip at 30 litres/tree/day for mature cashew plantations (10 to 15 years) is recommended.

Terminal drought : The rainfall deficit at terminal phase or cessation of rains at early stage also adversely affects the cashew nut yield particularly in late maturing varieties. To maintain the proper soil moisture regime, the harvesting of rain water and recycling them during deficit period is suggested. Moreover, adoption of soil conservation measures and installation of drip wherever water source is available will be helpful.

Source : NHM

Last Modified : 3/1/2020

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