Problems and management of citrus orchards - in arid zone of Punjab
A K Sangwan, M K Batth and Sashi Pathania
Citrus fruits have a prominent place among fruits of tropical and subtropical climate and are being grown extensively in this region of the world. In India citrus is the third largest industry after mango and banana and occupies a place of considerable importance in the economy of India. In Punjab fruits are grown in an area of approximately 79 thousand ha. Among them citrus fruits have a prominent place and is grown over an area of 52 thousand ha with production of about 11.65 lakh metric tons. The citrus industry is predominantly concentrated on cultivation of mandarin cv. Kinnow as it has wide adaptability, precocious bearing habit, high yield and excellent fruit quality. Moreover the enthusiasm of fruit growers to take up its cultivation on a large scale has resulted in rapid increase in area under its cultivation. But with the passage of time fruit growers of this region are facing problems of fruit drop, high water table, salinity, Phytophthora and unavailability of good nursery plants. As a result of which plants start declining at an early age. So, an attempt has been made to present the relevant information in regards to overcome these problems.
Fruit drop is a serious problem in citrus. It is mainly of two types physiological and pathological fruit drop. It mainly occurs in three distinct phases. The first drop occurs soon after fruit set and second drop occurs during May and June, which is severe in hot dry summer. These two drops are not of much concerned to the farmers. The third drop also known as pre-harvest fruit drop occurs during September-October causes serious losses to citrus growers. The first and second drop is occurs mainly due to physiological reasons and fruit drop occurs after June till maturity is primarily due to pathological reasons. Pathological fruit drop has been further aggravated after rains in Punjab due to fungal infection.
- Pruned and burn the deadwood after harvesting to avoid fungal infection.
- In bearing orchards, plants are sensitive to drought stress during summer month’s causes increased June drop, wilting and abscission of leaves, and reduces fruit size and lower juice content. So irrigate the field timely.
- Spray the trees with 1250ml Ziram 27 SC or 500 ml Propiconazole 25ECor 500 gm Bavistin 50WP + 5 gm 2,4 D (Sodium salt of horticulture grade) using 500 litres of water/Acre in mid April, mid August and mid September. Also give two additional sprays of 1250 ml Ziram 27 SC or 500 ml Propiconazole 25ECor 500 gm Bavistin 50WP in end July and end September. If there are broad leaf crops grown nearby, then use GA3 @ 20 ppm instead of 2-4D.
High water table and salinity
Water table of this area also rises up to an alarming situation which adversely affecting the Kinnow plantation of the region. The situations become worsen during rainy season. Because for root health and growth, the proper amount of air is as important in the soil as water. Roots need to “breathe”, and too much water can suffocate them as well as become sites for fungal disease and water molds to cause root rot and other issues. Even when, water table goes below the rootzone of the plants, it continually affects the plants severely for many years due to the salt accumulated by rising water table. Another major region for fruit drop and decline in Kinnow mandarin is high soil pH which governs the nutrient availability to the plants. As most of the soil of this area have pH more than 8.0. Which adversely affect the uptake of nutrients particularly micro nutrient from the soils. Moreover during the exceptionally low rainfall year and non availability of canal water, farmers use underground brackish water for irrigation which causes accumulation of salts in the root zone. It resulted in to toxic effect on Kinnow mandarin and plants showed declining symptoms. Under such conditions leaching of salt is necessary to protect the plants.
As orchard cultivation refers to the careful management of the orchard soil in such a way that the soil is maintained in a good condition suitable to the needs of the tree with least expenses.
- Avoid new plantation in those areas where water table is high, if necessary go for ridge plantation with high density.
- The fruit trees are quite sensitive to flooding conditions. Undue irrigation of trees also causes leaching of nutrient from the top of the soil to down layers and thereby reducing the fertility of the soils.
- It is probably best to plant a green manure crop between the trees early in the rains and plough it into the soil towards the end of monsoon season, addition of FYM also have beneficial effect on such types of soils. Green manure crops like Sunhemp, Cowpea, Daincha, etc. could be used for this purpose.
- In such types of soils use of sulphur based fertilizers like SSP, SOP and Ammonium sulphate proved to be beneficial. Besides these fertilizers use of wettable sulphur powder also helps to overcome the problem. Leaching of salts is also an effective tool to control the toxic affect of salts, accumulated either through high water table or with the ground water irrigation. It can be done by using flood irrigation (as and when available) with canal water once a year to avoid stress to plants.
The spread of Phytophthora (Gummosis); the most serious diseases of citrus is related to the moisture status in the citrus orchards. Affected trees show symptoms of foot rot with profuse gumming, trunk girdling, pale green foliage, stunted growth flushes and twig die-back. Most of the Kinnow growers underestimate the extent of damage that phytophthora can cause in the soil by killing the feeder roots. This hidden damage can seriously jeopardize the flourishing citrus industry, causes moderate to heavy destruction of kinnow orchards and also reduces the life span, quality and yield of tree.
- The disease is soil-borne and once it enters nurseries and orchards soil it generally become difficult to eradicate. So ‘Prevention is better than cure’ should be kept in mind.
- Obtain the planting material free from phytophthora
- Drip irrigation system should be adopted in orchards to avoid phytophthora foot/ root rot and their further expansion from one plant to another effectively.
- In case of flood irrigation care should be taken to avoid direct contact of water to the tree trunk since the spread of citrus foot rot is directly related to the high soil moisture content. So a gentle slope from tree trunk to the drip line of the trees may be given.
- Before planting, earthen ball should be dipped in 0.25% solution of Ridomil Gold MZ 68WP or Curzate M8 or Metamil 72WP or Matco 8-64.
- Use fungicides Ridomil Gold MZ 68WP or Curzate M8 or Metamil 72WP or Matco 8-64 25g per tree in 10 litres of water for drenching twice in February-March and July-August. Trunk paint can be combined with drenching.
- Foliar sprays of Aliette 80WP during April and September effectively control the disease.
Fruit yield and life expectancy of the plants can also be affected by vigour of nursery plants. As now a day’s demand for nursery plants increased many fold. Due to increase in demand of nursery plants large no of nurseries grown up in the region which are supplying unauthentic plant material to the growers. Quality planting material is the prerequisite for high yield and quality fruit production along with future life expectancy of plants. The grower sustains substantial losses due to insufficient supply of good planting material. Because success of any orchard mainly depends upon the availability of right type of planting material. Initial planting material is the basic requirement on which the final crop depends both in quality and quantity. In case, any mistake made during initial years, cannot be rectified in subsequent years and will cause everlasting damage to productivity and income of the orchardists.
Ensure the authenticity of planting material before going for new plantation. The Punjab agricultural university has been maintaining various nurseries throughout the state to meet the requirement of quality nursery plant of citrus, the list of which are given in table-1. July to September is the best time for new plantation. So purchase the quality plants from these nurseries and plant them timely in the field to avoid any mortality
Table 1: List of nurseries of PAU for citrus plants
Name / Place
Regional Research Station, Abohar
Regional Research Station, Bathinda
Department of Fruit Science, PAU, Ludhiana
Fruit Research Sub-Station, Jallowal and Lesriwal