Citrus are the very considerable fruit in Pakistan according to its production and area. Pakistan is ranked eleventh number as a citrus fruit producer while sixth largest producer of kinnow (Citrus reticulata) and oranges (Citrus cinensis) in the World, with 2.1 million tons production. In 1950, it introduced in Pakistan and due to this fruit Sargodha called California of Pakistan. Citrus fruits can be utilized as a table purposes (fresh fruits), jams, juices, marmalades, and also have medicinal value.
There are number of insect pests that attack on citrus plant among them Citrus psylla (Diaphorina citri, Psyllidae: Homoptera) is serious insect pest of citrus and present in tropical and subtropical region. It is brown, tiny insect 3 to 4 mm long. Due to its smaller size, it can easily break out with wind and can travel for a miles. Yellow orange color eggs are laid by female on the upper side of new growing shoots. Eggs are hatched in four days. The life of adult is 1 to 2 months. When adult feel a little disturbance, it will fly or jump for a short distance. Active season of citrus Psylla is spring and after monsoon while less active in winter.
Their nymphs particularly feed on new leaves. Adult suck the cell sap from leaves and stem of citrus plant. The fruits come down with both qualitative and qualitative loss. After attack, citrus leaves become curled, defoliation occurs, flower start to drop and even that death of branches from tip is known as die back. It produces honey dew that coats the leaves of the plant which enhance to grow sooty mold. By injecting toxin during feed that provide basis cut off the tips of new leaves. Citrus Psylla (fifth instar nymph) is vector of plant disease which is citrus greening also known as haunglongbing (HLB) or yellow dragon disease which is very fatal to citrus plants caused by a bacterium that disturb the plant capability to move nutrients. Where the disease is endemic, citrus trees decline within 5 to 8 years after planting. Kinnow and sweet oranges are more susceptible to this disease. Citrus greening disease, inhibit citrus fruit from maintaining proper color. The bottom portion of the fruits remains green. Leaves turn into yellow in color. It posses the fruit to small in size, irregular shape, with terminate seed and harsh juice. The yield of plant is severely reduce and the fruit which we get very poor in quality. Seed abortion is a very common phenomenon in this disease. By deficiency of nitrogen, the peal of fruit becomes thin. Copper helps to increase vitamin C (ascorbic acid) while its deficiency is responsible for corking of fruit. In citrus fruit, consumer demand appearance, shape and taste.
The Board Parameters (International Market Preferences) are:
- Size: 30-48 counts per 10 kilogram of fruits
- Texture: stable or firm
- Color: Red
- Seed: Seedless
- Rind: smooth, spot free and easy peeler
- Quality parameters: Total Soluble Salts (TSS) 12%, Sugar contents 9%, Acidity (maximum) 01
Due to citrus Psylla and citrus greening disease attack, we do not attain proper size, color, texture and other quality parameters and unable to fulfill above mentioned requirements. The foreign countries show dissatisfaction in the quality of citrus (kinnow) due to insect pest and disease problem. The citrus producers have no option except to sell their products locally and bear financial problem because only 10% of total production is exported. Pests and diseases play an important role economically.
Pakistan is a developing country where limited resources and mostly farmers are not educated. We should require combine effort to eradicate pests and diseases because it is not a work of a single man. As we know many diseases spread through insects, so we need to identify and control particular those insect pests well in time to save our agricultural industry.
*Nawaz Haider Bashir, **Waheed Ul Hassan, ***Talha Nazir, ****Mureed Abbas, *****Naveed Mushtaq *, **, ***, ****Department of Entomology, ***** Department of Plant Breeding and Genetics ,University of Agriculture, Faisalabad