ROLE OF PRUNING IN CITRUS, TIMING AND ITS IMPACT ON TREE AND FRUIT

*Muhammad Shafique Khalid, *Muhammad. Amin, *Omer Hafeez, **Muhammad Umar and **Faheem Haider

* PhD Scholar, Institute of Horticultural Sciences, University of Agriculture Faisalabad

** M.Sc Scholar Institute of Horticultural Sciences, University of Agriculture Faisalabad

Pruning fruit trees is a technique that is employed by gardeners to control growth, remove dead or diseased wood or stimulate the formation of flowers and fruit buds. Pruning of tree fruits and vines is a horticultural practice handed down from ancient time. It has in common the objectives of manipulating various aspects of vegetative and fruiting behaviour. Some of the benefits traditionally attributed to pruning and girdling in the practical culture of citrus have been called into question by field research in the past few decades.

Citrus is a perennial crop. As long as the trees remain healthy, they can flower and fruit for years on end, some times for as long as twenty or thirty years (Mazhar and Nawaz, 2006). However, if the trees are not maintained at a proper size, the height and canopy shape of mature trees in a citrus orchard will not be uniform and the branches will be too crowded. In a crowded orchard, disease and pests can spread quickly. Fruit quality tends to be poor, and trees may not bear fruit every year. A proper training and pruning program is essential for the maintenance of a healthy and productive orchard.

Benefits of pruning in citrus

The major benifits of pruning in citrus include:

1. The total effective leaf area is increased resulting in increased photosynthesis by exposing the leaves to light and air.
2. The water use efficiency and the conversion of available plant nutrients is increased.
3. By removing diseased or infested branches and exposing leaves to light and air, a good training and pruning program helps control pests and diseases in citrus orchard.
4. Proper pruning of the tree keeps it in the right size.
5. It also increases the vigor of the tree, enhances its tolerance of various stresses, and helps maintain the most efficient balance between vegetative growth and fruiting.

Pruning and skirting (removal of low-hanging limbs) affects on canopy temperature, relative humidity (RH), and fruit yield and quality of Orlando' tangelo trees (Citrus paradisi Macf. x Citrus reticulata Blanco). Pruning increased the percentage of large fruit and reduced the percentage of small fruit. (Morales et al., 2000).

The alternate tendency exists across all varieties of the citrus. To attenuate alternate bearing, pruning and fertilization are processes the only options which growers can exploit. For pruning to be effective, it must be done after the end of an “off” or light crop year, i.e., prior to the season of anticipated high production. It should not matter whether the pruning is conducted before or after the bloom, as the results should be about the same, reduction in production during the season following pruning (Mazhar and Nawaz, 2006).

Eissenstat and Duncan (1992) reported that total reducing and ketone sugars (free fructose, sucrose and fructans) in the fine roots were less in pruned than unpruned trees 20 days after pruning, but not thereafter. By 30 days after pruning, at least 20% of the roots of the pruned trees at a soil depth of 9 to 35 cm apparently died. By 63 days after pruning, root length density had recovered to that of the unpruned trees, although starch reserves were 18% less in the fine roots of pruned than unpruned trees at this time.

Growers should select the correct time for the pruning. Since citrus trees are evergreen, they do not have a period of true dormancy. However, the metabolism of the tree is less active in the period after fruit harvesting. This period of reduced metabolism activity is the time to prune. Light pruning can also be conducted at other seasons to remove unwanted and overcrowded shoots.

Tree age is another important factor that should be taken into account, because the tree’s response to pruning varies according to age (Mazhar and Nawaz, 2006). Therefore citrus growers have to recognize the characteristics of the different cultivars they are growing in order to select the best training and pruning system for their orchards.

References:

Eissenstat D.M and L.W Duncan.1992. Root growth and carbohydrate responses in bearing citrus trees following partial canopy removal. Tree Physiol. 10(3): 245-57.
Mazhar, M.S. and M.A. Nawaz. 2006. Pruning as a tool to improve yields in citrus. Pakistan Horticulture. 4(1): 23-25.
Morales, P., F.S. Davies and R.C Littell. 2000. Pruning and skirting affect canopy microclimate, yields, and fruit quality of 'Orlando' tangelo. Hort Science. 35: 30-35.

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A futuristic approach to establishing healthy citrus orchards

By M Usman and M Monis

Citrus stands second after grapes in the world in terms of area and production. Citrus world leaders include US, Brazil and China. China with 15 percent and Brazil 7.0 percent have much higher area under citrus, however US is leading in per hectare yield producing 31 tonnes per hectare based on better technology and century old citrus nursery certification programmes. Citrus holds 19 percent area under cultivation producing 25 percent of total fruit production in Pakistan. However, static yield 8-10 tonnes per hectare of citrus for the last 60 years is a big question. In recent past there was slight increase in per hectare yield 2.0 tonnes per hectare that may be due to better management practices and high density plantations by progressive growers. Similarly if we look at global guava industry, Pakistan is merely producing 8.0 tonnes per hectare as compared with 21-28 tonnes per hectare in Taiwan and Brazil, respectively. Even India is producing 2-3 tonnes per hectare more as compared with Pakistan. In Pakistan 80 percent of the crop is contributed by Punjab province suggesting that this crop is very important for Punjab fruit industry. Pakistan is earning Rs 13.8 billion foreign exchange by guava exports and processing industry is also investing in this sector. However, unfortunately there is a very sharp decline observed both in area (1,800 hecates) and production (3,400 tonnes) from 2007-2011 that needs to ponder. 

Health status of our fruit plant orchards is alarming and poor health leads to early termination of plants productive life leading to a decline in fruit industry. Faulty nurseries, defective management, poor cultural practices, and other biotic and abiotic problems are considered as the major factors for collapse of the fruit industry. Biotic factors include different insects and diseases caused by pathogens like fungi, bacteria, nematodes and viruses particularly in citrus and guava. Phytophthora, Fusarium sp, Citrus TristezaVirus (CTV) and Citrus Greening Disease (CGD) are major alarming problems to citrus industry in the country and citrus exports have declined to merely 110,000 tonnes during 2007-08. Any damage to citrus and guava industry may yield huge losses to the country’s economy and stakeholders.
The maintenance of fruit industry and establishing new orchards is dependent upon regular availability of healthy and sanitation plant material. Mostly the edible scion cultivars in citrus show less tolerance to soil borne biotic threats and are therefore grafted on tolerant-resistant rootstocks to provide better root system. Like citrus rootstock guava is commercially raised from seeds and guava industry of Pakistan is seedling based. Guava is facing serious decline issue which is directly related to soil borne fungal problems like Phytophthorasp, Fusarium sp and in some cases nematodes. Fusarium sp is reported to cause drooping and wilting of guava leaves in recent studies. Our citrus and guava industry is dependent upon faulty conventional nurseries. There is yet no concept of container grown nursery in guava having sterilised potting media in the nurserymen and the growers. Sanitation situation is comparatively better in citrus since the concept of container-grown nursery is getting popular gradually. Further, Agri-Business Support Fund is also supporting establishment of certified plant nurseries with the help of USAID and many industrialists and progressive growers are trying to establish this highly lucrative business emerging as a future industry. So this is the right time to extend this concept and technology to guava and to other fruit crops to save our fruit plant industry from soil borne disease spread.

Most of our commercial fruit plant nurseries are not following standard sanitation practices thus acting as a source of disease spread particularly soil borne and seed borne diseases in addition to insects and microbial infestations in plants. There is absolutely no concept of media or soil treatment and rootstock seed treatment. Elite guava selections are producing fruit eight to 10 months a year if the growers are not sacrificing summer crop. This consistently regular bearing habit of selected guava cultivars has enhanced fruit growers’ interest in this nutraceutically important fruit crop, which is highly rich source of ascorbic acid as well. Guava growers are fetching good prices for their orchards from the tenants and people are interested to plant new orchards particularly in Southern areas of Punjab from District Faisalabad towards Sadikabad and in Sindh. Shirkpur (Sheikhupura) is the guava hub in Punjab holding great genetic diversity but badly hit by guava decline issue. The root cause of many problems seems to be running nurseries in non-professional traditional ways. The issue could be resolved by providing clean and healthy containerised nursery plants free from soil borne diseases to the progressive growers and establish model nurseries for the stakeholders for demonstration following Florida, California and Australian nursery production models.

Container grown fruit plant nursery offers several advantages over conventional system of plant propagation in the field. Fruit plants can be propagated even in areas with poor soil, improper climate and helps in efficient use of the given space. These plants are easily portable without disturbing the plant root system. Container type and size could be modified according to the crop requirements. Potting media used is highly nutritious and free of soil borne pests thus blocking dissemination of soil borne diseases from nursery to the orchards. Container grown nursery is less labor intensive and provides absolute weed control. Round the year nursery production is possible provided plants are raised in controlled environment.Based on these facts, a similar nursery model has been established in the Institute of Horticultural Sciences funded by joint venture of USDA and Endowment Fund Secretariat, University of Agriculture, Faisalabad. A locally fabricated environment-friendly model steam sterilisation unit-first of its kind- has been installed for potting media sterilisation and healthy citrus and guava nursery establishment in plastic containers is in progress. The technology is being transferred to all the stakeholders through training courses, literature and media to promote containerised nursery culture. One of our collaborators has established similar model nursery for mango and citrus in Sadikabad. The resulting orchards will have long productive life, higher yields, quality fruits and provide more income to the farmers and other stakeholders. Conclusively there is dire need to shift from conventional field propagation methods to container grown plant production system in both citrus and guava since ‘prevention is better than cure’.

Courtesy: Daily Time Pakistan

Muhammad Usman Rana (Author)

About Author:

Muhammad Usman Rana Worked at University Of Agriculture Faisalabad, This article of Mr Rana Taken from Daily Time, this article is very informative.

Legume Crops | Salinity and Drought Management

By: Hussain N., G. Sarwar, H. Schmeisky, Salim Al-Rawa

The predicted global climatic changes anticipate rise in temperature, cyclones, floods, variability and unpredictability of rainfall, droughts, and melting of ice. Expected desiccation and rise in temperature will be resulting in high evapo-transpiration. The drier regions of the globe may become further drier. Consequently, it will become highly difficult for water scarce countries to face this challenge. Surface water scarcity will divert pressure on utilization of groundwater, the major part of which is not of safe and usablequality. Hence, soil and water salinity/ sodicty may enhance that will negatively affect soil characteristics (chemical and physical) and consequently reduce growth and yield of crops. Legumes are the most sensitive group in this regard and are expected to affect largely.

Therefore, special management practices must be adopted to cope with the global climatic changes. Suitable hydraulic options (leaching and drainage), appropriate agronomic practices like; leveling, deep plowing, rainfall harvesting, application of organic matter, balanced nutrients, suitable sowing methods, mulching and planting geometry and appropriate irrigation technologies; scheduling, modification of irrigation system (shifting from surface irrigation to drip, sprinkler or sub-surface), cyclic use of good quality and brackish water have to be adopted. The changing situations will also require wise decisions like; selection of crop sequences that can withstand salinity stresses and inclusion of legumes in the crop rotations. Understanding of genetic variability with respect to salt tolerance will be necessary. Starting strong breeding programs to achieve this objective supported with modern approaches; Biotechnology, Mutation and Genetic Engineering will necessarily be desired from right now

Citrus Fruits of Pakistan

Citrus Fruits of Pakistan

 

Citrus are the fruits belonging to the Rutacease family and mostly from the genus Citrus which are usually mix of sweet and acidic fruits. They are widely cultivated fruits in the world with areas under cultivation and production increasing greatly from 2000 - 2010. Citrus is ranked world number 21st in Pakistan with respect to its area and production among fruits. There is a huge demand from both the fresh and processed oranges by the consumer.

According to FAO, Brazil is the largest producer of citrus in the world, followed by China and USA, data for Pakistan is not available. In Pakistan, it is cultivated its 95% area of cultivation is in Punjab because of favorable temperature and environmental conditions and the total production according to approx. 1.8 annually on an estimated area of 194,000ha with the per acre yield standing at 4.6 tons.

IMPORTANCE AND USES:

1. Sweet orange, mandarin and grapefruit are eaten fresh or processed for squash (sweetened fruit juice) and juice preparation.

2. Lemon and lime are acidic in nature and largely used in preparation of culinary products such as pickles and for flavoring food items. They are also processed for juice, squash and lemonade.

3. Citrus fruits are a rich source of sugar, citric acid and vitamin C, and they possess valuable medicinal properties, being used in the prevention of colds and malaria and to promote blood coagulation.

 

MAJOR CITRUS GROWING AREAS IN PAKISTAN

PUJAB

Districts of Sargodha, Jhang, Sahiwal, Lahore, Multan, Gujranwala, Sialkot, Mianwali

SINDH

Districts of Sukkur, Nawabshah, Khairpur

KHYBER PAKHTUNKHWA

Peshawar, Mardan, Swat, Hazzara, Nowshera, Swabi

BALOCHISTAN

Sibbi, Makran, Kech

 

CITRUS SPECIES BEING CULTIVATED IN PAKISTAN

1. Grapefruit (Citrus paradisi Macfad.)

Local Varieties: Mash Seedless, Duncan, Foster and Shamber

2. Mandarin (Citrus reticulata Blanco)

Local Varieties: Fuetrells Early and Kinnow

3. Sweet Orange (Citrus sinensis (L.) Osbeck)

Local Varieties: Mausami, Washington Navel, Succri, Red Blood, Jaffa, Ruby Red and Valencia Late.

4. Bitter Orange (Citrus aurantium L.)

Also called, Seville orange, Sour Orange, Marmalade orange or bigarade orange.

5. Lime (Citrus aurantifolia (Christm.) Swingle)

Also called, Key Lime, Bartender's lime, Omani lime or West Indian lime

Local Varieties: Sweet Lime and Kaghazi Lime

6. Lemon (Citrus Limon (L.) Burm. f.)

Local Varieties: Eureka and Lisbon Lemon

7. Rough Lemon (Citrus jambhiri Lush.)

It is the most common rootstock for propagation of citrus in the subcontinent.

8. Kinnow (It is a Hybrid of Citrus nobilis and Citrus deliciosa)

It was first developed at the Citrus Research Center at the University of California in 1935 and then Punjab Agriculture College and Research Institute Faisalabad (then, Lyallpur) Pakistan, introduced it in the sub-continent in 1940.

It is a very famous citrus plant knows for delicious juicy fruit. Environmental and soil conditions are ideal for kinnow in Punjab. Hence the kinnow is a prime export fruit of Pakistan which is in great demand due to its juicy, soft, scented and refreshing fruit not found anywhere else in the world. Seedless kinnow is also very popular.

Socio-economic correlates of pesticide usage: the case of citrus farmers

Socio-economic correlates of pesticide usage: the case of citrus farmersGhulam Yasin, Muhammad Aslam, Ijaz Parvez and Safina Naz
University College of Agriculture, Bahauddin Zakariya University, Multan 60800, Pakistan,

Abstract: The socio-economic factors affecting adoption of pesticides on citrus trees in Sargodha Division, Pakistan was studied. Six villages were selected (three from each sub division) for data collection. Overall 150 orchard owners (25 from each sample village) were interviewed. Data were analyzed using SPSS programme. Gamma test and chi-square were used to check the direction and magnitude of relationship between independent and dependent variables. Among the sample, 48% respondents were spray users. The socio-economic factors that influenced farmer’s receptivity to citrus spray were age (negatively correlated), education (positively correlated), social status (positively correlated), farm size (negatively correlated) and farming experience (negatively correlated). By incurring Rs. 3,600/= per ha on spray farmers received Rs. 19,000/= as an incremental benefit. Marginal rate of return indicated that by spending Re. 1.00 on spray farmers would get an increase of Rs. 5.27 in their income.
Keywords: adoption, citrus, pesticide, socio-economic correlates.

INTRODUCTIONCitrus, among various fruits grown in Pakistan, is considered to be the most important for better economic earning and its dietetic value. The importance of citrus has generally been recognized throughout the world. Citrus has generally been a source of foreign exchange earning and its domestic need is also growing in the country. As a result of its importance more area is brought under cultivation to enhance its production.
Area under citrus is increasing substantially every year but production is increasing at a very low pace. The production of citrus was consistent from 1994 to 1998. The fruit yield during 1994-95 was 10,135.0 kg per hectare and after five years (in 1999-2000) it fell down to 9,829.0 kg [Pakistan Agricultural Statistics 2001]. In Pakistan, average productivity is 9.5 tones per hectare [Pakistan Agricultural Statistics 2001], which is very low as compared with developed countries like United States, Japan and Australia. In developed countries average yield is approximately 40 tons per hectare [FAO 1998]. There are a number of obstacles in obtaining higher yield of citrus. It is generally thought that the primary factor responsible for decrease in citrus production and quality is poor plant nutrition. Low yield in Pakistan is also attributed to disease incidence and insect pests’ attack and poor or no pest management practices by the farmers [PARC 1989]. AKRSP [1987] revealed that prior to introduction of pest and disease control technology, not only fruit production was low, but quality was also of low standards.

To increase yield and improve the quality of citrus in Pakistan, there is a need to introduce proper pests and disease control technology. It has been reported that adoption of insect and disease control methods has not only helped to increase the quantity of fruit but improved the quality as well [Cheema et al. 1989, Cheema and Asghar 1990]. Thus, there is a need to introduce disease and insect control technology among all the citrus growers in the country. Not much work has been done in Pakistan despite significant importance of citrus fruit. So, the present study aims at filling this gap and identifies the characteristics of the citrus growers who are using spray and examines the impacts of spray on citrus in Sargodha district.
Some studies have been conducted on the adoption of plant protection measures against pests and diseases of different fruits but no specific work has been carried out on the use of pesticide spray and its socio-economic correlates. Related work is reviewed as follows:
Milne and Willers [1980] treated two mature Valencia orange orchards with Fenamiphos 40% E.C. in 1978. In 1980 these were retreated and there were significant increase in yield, i.e. 83 to 130 kg per tree. Rashid [1980] studied some personal and socio-economic factors associated with adoption of recommended agricultural practices in Rural Egypt. He reported that education and income were associated with the uses of pesticide. However, age of farmer was not related to the said uses. Ahmad [1992] conducted a study on the adoption of plant protection measures by citrus growers and found that there was a positive relationship between age group, educational level, social status, size of holding, size of orchard and adoption of plant protection measures.
Cheema et al. [1989] in their study in Gilgit district found that net benefit for apple tree received was Rs. 111/= per tree with a spray cost of Rs. 5.00 per tree, this gives a ratio of 1: 22. Cheema and Asghar [1990] reported that on the basis of cost structure involved in spray application to citrus, it was found that an average return to investment on citrus spray was 1 to 2.60.

MATERIALS AND METHODS
The average production of citrus in Pakistan is 1960.80 (‘000’ tones) per annum. The Sargodha district is producing 744,000 tones (37% of Pakistan’s total production) citrus fruit per annum [Pakistan Agricultural Statistics 2002]. Based on information gathered from the Revenue Department of the District Management Office two sub divisions were selected. Six villages, three from each sub-division, Sargodha and Bhalwal were taken randomly. Over all samples of 150 orchard owners (25 from each village) were drawn. The data were collected with the help of personal interviews based on structured questionnaire. Questionnaire contained information on the socio-economic factors, which were likely to influence the adoption of pesticide spray on citrus. Farmer’s age, education (years of schooling), social status, farm size and farming experience were used as the main indicators for the use of pesticide technology.
Fieldwork was done in August-September 2001. Using SPSS program, data were analyzed to identify the various socio-economic characteristics of the users and non–users of pesticides application. Gamma statistics and chi-square test were also used to check the direction and magnitude of relationship between independent and dependent variables. Calculations were made by using the following formula:

Gamma = (Ns – Nd) / (Ns + Nd)
Where
Ns = number of same order-pairs.
Nd = number of different order-pairs.
If gamma is equal to 1.0, it means that dependent variable is explained fully by independent variable without error.

Chi – Square Test:
X2 = ∑(o – e) 2 / e
Where
o = observed frequency
e = expected frequency
Both Gamma and Chi-Square values were considered significant at 0.05 probability level.

RESULTS AND DISCUSSION
It was found that over all 48% of the respondents were adopters of spray based on the parameters given in Table 1. The relationship between different socio-economic factors and adoption of pesticides spray is presented in Table 1. The relationship between age and adoption of pesticide spray is strongly negative. It is clear that farmers between age group of 22-40 adopted the pesticide spray more (57.6%) than elders. Our results are similar to those of Cheema and Asghar [1990].

A strongly positive relationship was found between education level and adoption. Farmers with higher education were better adopters (61.5). These findings are in accordance with what Ali [1972] and Cheema and Asghar [1990] have reported.

Size of holding is one of the main determinant of financial status of a farmer, which in turn affects farmer’s receptivity to adopt modern production practices, like uses of pesticides. The relationship between adoption of pesticide spray and size of holding was weak, which indicates that size of holding did not affect the adoption of citrus spray in the study area.

There was a strong and negative relationship between farming experience and adoption of insecticide spray. Farmers adopted pesticide spray when they had less farming experience as compared with those having more farming experience. The relationship between social status and adoption was strongly positive, which shows that higher social status leads to adoption of pesticides spray more as compared to low social status. These findings are similar to those of Cheema and Asghar [1990].

Data presented in Table 2 indicate the difference in production between users and non-users of pesticides. Non-users had 17 tons citrus yield per hectare, valuing Rs. 86,000/= whereas users produced 21 tons per hectare, valuing Rs. 105,000/=. A significant difference was found in production by incurring Rs. 3,600/= on pesticide spray. Farmers were able to get extra 4 tones of citrus per hectare.

Data presented in Table 3 reveal that farmers, who made use of spray had gross benefit of Rs. 105,000/= per hectare by spending Rs. 3,600/= as a cost of spray. So, by incurring Rs. 3,600/= per hectare farmers received Rs. 19,000/= as an incremental benefit. Marginal rate of return on citrus spray is 1:5.27 showing that by increasing cost on spray per hectare by Re. 1.00 farmers were able to get an increase of Rs. 5.27 in their income. Results of the study were quite encouraging.

ONCLUSIONS AND POLICY IMPLICATIONS
The present study is an attempt to identify the socio-economic factors affecting the use of pesticide, which ultimately affects the rate of return per unit of investment on citrus spray. Information on the socio-economic factors that were likely to influence farmer’s receptivity to citrus spray was gathered and was analyzed. Farmer’s age had negative and strong correlation with pesticide usage; it implies that farmers used citrus spray in younger age. The positive and strong correlation was also found with education. Educated farmers used more sprays than those with little education or uneducated. Size of holding had no effect on usage of citrus spray, while strong and negative relationship has been found with farming experience. Farmers used spray when they had less farming experience. In case of social status farmers with higher social status used spray. As far as the economic benefit of pesticide use is concerned farmers, who made use of spray, had gross benefit of Rs. 105,000/= per hectare by spending Rs. 3,600/= per hectare. So, farmers received Rs. 19,000/= as an incremental benefit. Marginal rate of return on citrus spray is 1: 5.27 showing that by increasing cost on spray per hectare by Rs. 1.00 farmers were able to get an increase of Rs. 5.27 in their income.

Taking all the findings into account following suggestions are given for policy implication:
1) The extension people should play an important role for the dissemination of knowledge regarding pesticide applications and should create awareness among farmers for the said application, so that farmers could get benefit and have better production by reducing losses.

2) The pesticide should be made available to the farmers at the proper time and proper places.

3) The application of pesticides to citrus fruit requires mechanical sprayers, which are expensive, and beyond the purchasing power of farmers, so these should be made available at cheaper prices.

References
Ahmad, I. (1992) “A study into the adoption of plant protection measures by the citrus fruit growers of Toba Tek Singh Distt.”, Report Department of Agriculture Extension, University of Agriculture, Faisalabad.

AKRSP (1987) “Fifth Annual Review”, Aga Khan Rural Support Programme, Gilgit, Northern Areas.
Ali, A. (1972) “Study of some of the selected socio-economic factors which influence the adoption of improved agriculture practices by the farmers”, Report Department of Agriculture Extension, University of Agriculture, Faisalabad, Pakistan.

Cheema, A.M., Khaleel, A. and Alam, M. (1989) “Income Impact of Spray Package in Gilgit”, A report, Department of Rural Sociology, University of Agriculture, Faisalabad, Pakistan.

Cheema, N.M. and Asghar, M. (1990) “Economic Impact of spray on Citrus”, Department of Rural Sociology, University of Agriculture, Faisalabad, Pakistan.

FAO (1998) “Report on fruit production in Pakistan”, Food and Agriculture Organization, United Nation Publications, July 1998.

Govt. of Pakistan (2001) “Pakistan Agricultural Statistical Year Book”, Ministry of Food and Agriculture, Islamabad, Pakistan.

Govt. of Pakistan (2002) “Pakistan Agricultural Statistical Year Book”, Ministry of Food and Agriculture, Islamabad, Pakistan.

Milne, D.Z. and Willers, P. (1980) “Yield and fruit size increase due to control of citrus nematode with phenomiphas”, Information Bulletin, Citrus and sub-trop. Fruit Res. Inst., 90, 11-14 [Hort. Abst., 51(9), 1981, 647].
PARC (1989) “Citrus Research in Pakistan”, Pakistan Agriculture Research Council, Islamabad, Pakistan.

Rashid, M. (1980) “Some personal and socio-economic factors associated with the adoption of recommended agricultural practices in Rural Egypt”, World Agric. Economics and Rural Sociology Abst., 19(12), 800.

Source: Journal of Research (Science), Bahauddin Zakariya University, Multan, Pakistan. Vol.14, No.1, June 2003, pp. 43-48 ISSN 1021 1012