37. Impacts of Cotton Leaf Curl Virus on the Yield of Cotton In Pakistan

 Cotton Leaf Curl Virus

Cotton Introduction:

    Cotton is a type of natural fiber that grows in a protective case called a boll, around the seeds of plants belonging to the Gossypium genus in the Malvaceae family. The fiber is composed mainly of cellulose, with small amounts of waxes, fats, pectins, and water. In the wild, the cotton bolls help to spread the seeds.

    This versatile fiber is typically spun into yarn or thread and used to create textiles that are soft, breathable, and long-lasting.

History of CLCuV:

    Cotton leaf curl disease was initially discovered in Multan in 1967 and was not considered a significant threat until 1987. In 1988, however, the disease caused damage to the cotton crop on 60 hectares in the Multan district, leading to concerns about its potential impact. The following year, the disease affected 200 hectares, and by 1990, it had spread to 800 hectares. The situation worsened in 1991, when the disease appeared in epidemic proportions, affecting an area of 14,000 hectares in the Multan, Khanewal, and Vehari districts. 

        The disease continued to spread, with over 485,000 hectares affected in 1992, resulting in a decrease in production and significant financial losses for the country. In 1993, the disease spread throughout the entire Cotton Belt of Punjab, causing varying levels of damage on 889,000 hectares. The disease was also reported in D.G. Khan and Sindh.

Symptoms:

• The primary symptom of Cotton leaf curl disease is the thickening of the veins in affected plants. 
• Additionally, infected plants may display the yellowing of small veins on the underside of the leaves, as well as leaf curling. 
• In more severe cases, a cup-shaped leaf-like outgrowth may appear on the underside of curled leaves. 

• Early infection can lead to stunted plant growth and significant reductions in crop yield.

Spread or Transmission:

    The Cotton leaf curl disease is transmitted between plants through its carrier, the whitefly. This virus has the ability to thrive not only on cotton, but also on several other weeds and hosts, including ladyfingers (okra), eggplant, chilies, tomato, cucumber, tobacco, and melon during the off-season. The disease has the capacity to multiply on weeds and other hosts, as well as on plant debris from previous crops that are present during the season.

Control or Management:

• Planting multiple varieties of cotton.
• Growing tall varieties of cotton to minimize whitefly infestations.
• Clearing fields and the surrounding areas of weeds to reduce the availability of hosts for whiteflies and the virus.
• Regularly removing any CLCuV-infected plants to prevent the further spread of the disease.
• Applying nitrogen during sowing to promote initial plant growth.
• Ensuring adequate irrigation, especially during the hot months of May, June, and July, to prevent water stress and maintain growth rates.
• Irrigating each field separately to avoid the spread of the disease.
• Practicing crop rotation with non-host crops to reduce the buildup of the virus in the soil.
• After harvesting, plow all plant debris into the soil or burn them if possible.
• Apply a seed treatment with Imidacloprid 600 FS at a rate of 5 ml/kg and Thiamethoxam 250 g/kg at 25% w/w to effectively control the virus.
• To combat whitefly attacks (the vector of CLCV), use effective insecticides such as diafenthiuron 500 g/L at 47.2% w/w, imidacloprid 200SL at 250 ml/acre, or acetamiprid 20SP (e.g. Mospilan) at 125 gm/acre during May, June, and July to control the whitefly. Buprofezin has been proven effective against nymphs, while acetamiprid, diafenthiuron, and imidacloprid have been effective against whitefly adults.

Impacts of CLCuV on the Yield of Cotton:

• In 1991-92, the highest-ever production of cotton was achieved, with 12.8 million bales being produced. 
• However, in the following years, there was a downward trend in production, with only 8.04 million bales being produced in 1993-94 due to a severe outbreak of cotton leaf curl disease (CLCuV), which caused significant damage to the cotton crop. 
• Unfortunately, since then, a decline in yield due to CLCuV has been a regular occurrence every year, resulting in the loss of approximately 6.5 million bales over the last decade.
• Fortunately, due to an increase in the cultivation of relatively tolerant or resistant cotton cultivars, along with other remedial measures taken against CLCuV, the declining trend in cotton production has been checked and even reversed. 
• For example, in 1995-96, the country was able to produce 10.06 million bales of cotton. However, during 1996-97, production declined again to 9.35 million bales due to severe attacks from whitefly and leaf curl virus, as well as continuous hot and dry weather.
• With the increasing prevalence of CLCV in Punjab and its transmission by the whitefly (Bemisia tabaci), a monitoring program was launched in Sindh in 1996, with a focus on geminiviruses including CLCV. The disease was first detected near Ubavro, an area close to the Punjab-Sindh border. 
• Since then, the incidence of CLCV has been on the rise, spreading from Ubavro to other areas. The disease has now traveled as far as Sakrand, which is located about 450 kilometers away from the original site of its detection in Ubavro. 
• The spread of the disease over the past three years has been a cause of concern for farmers and agricultural authorities in the region.

References:

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36. Whip Smut of Sugarcane and Their Control

 Sugarcane

Introduction:

    Sugarcane is a valuable crop for growers as it serves as the primary source of white crystal sugar, and also provides alternative sources of sugar such as 'gur' and 'khandsari' (brown sugar). In addition, sugarcane tops can be used as cattle fodder, bagasse and leaf trash can be used as fuel, and the stubble and roots can serve as organic manure. Crop residues can also be utilized for mulch and compost. It is worth noting that sugarcane leaves are also used as a substrate for growing edible mushrooms.

    In Pakistan, sugarcane cultivation faces numerous challenges, including significant losses caused by various diseases. Over 50 diseases have been reported in sugarcane, with fungi, bacteria, viruses, and nematodes causing the most damage. The extent of losses varies depending on the crop variety and location, and cannot be ignored, neglected, or taken lightly as they can significantly impact the crop. These diseases can affect different plant parts, and their occurrence is influenced by a range of factors such as geography, weather, and time. Symptoms or signs of the diseases raise a concern about their potential effects on the quantity and quality of the sugarcane crop.

    Sugarcane, a crop grown in over 120 countries on around 26.27 million hectares, is the largest commercial crop globally. It yields approximately 1.90 billion tonnes worldwide, providing 80% of the world's sugar. The crop produces hundreds of tons of green matter per hectare annually, giving 75,000 million calories. However, sugarcane takes 12-14 months to mature and harvest, making it vulnerable to many biotic and abiotic factors, such as pathogens and insect pests that can reduce production by up to 20%. Fungal pathogens, in particular, pose a significant challenge, with over 100 fungi reported to cause sugarcane diseases.

Whip Smut of Sugarcane

Causal Organism:

    The fungal disease, known as smut, is attributed to Ustilago scitaminea. The fungus infects sugarcane plants via buds present on erect stems or sprouting buds in the ground. Once inside, the fungus establishes itself near the plant's growing points or meristems.

Symptoms:

• Sugarcane smut is identifiable by a black, whip-like structure that replaces the spindle leaf and grows from the sugarcane plant's growing point. Abnormal whips, sometimes containing flower parts, can also develop.
• The whips are produced in shoots arising from infected cane cuttings, contaminated soil, or side shoots from mature stalks. 
• The thin membrane of the whip eventually ruptures to release a mass of black spores, leaving behind a straw-colored core.
• Before whip formation, the youngest leaves undergo shortening and crinkling. 
• Infected plants tend to be stunted, and individual stalks appear thin and grass-like.

Disease Cycle:

    Sugarcane smut spreads through teliospores produced in the smut whip found in soil or on plants. Teliospores germinate in water and produce promycelium, which undergoes meiosis to form four haploid sporidia. The fungus is bipolar, producing two different spore types that must mate to create a dikaryon that infects sugarcane's meristematic tissue by penetrating bud scales. The fungus grows within the tissue, inducing flowering structures that it colonizes to produce teliospores. These structures transform into a whip-like sorus, covered by a silvery peridium that peels back to expose black-brown teliospores. These spores disperse via wind and repeat the cycle. Teliospores are reddish-brown, round or subovoid, smooth to moderately echinulate, and 6.5-8 um. Susceptibility to S. scitamineum populations in each area should be tested before distributing sugarcane cultivars.

Spread or Transmission:

    Sugarcane smut is mainly transmitted via wind-dispersed spores or by planting contaminated or infected cane cuttings. Typically, spores spread over short distances, up to 10-15 meters, but they can travel many kilometers during strong winds or cyclones. Spore transport on machinery and shoes is also feasible.

    Moist soil can support spore survival for only 2-3 months, whereas dry soil or other arid environments can sustain them for longer periods. The fungus remains viable within infected sugarcane plants as long as the host plant is alive, as it requires a living plant to produce spores.

Control:

1. It is advisable to avoid using sets from sugarcane plants affected by smut for planting.
2. Seed sets can be disinfected by immersing them in a solution of 0.1% mercuric chloride or formalin for 5 minutes, followed by covering them with a moist cloth for 2 hours. Other effective chemicals available in the market can also be used.
3. Internal infection can be eliminated by exposing sets to hot water treatment at 52°C for 18 minutes.
4. Sugarcane plants affected by smut should be uprooted and burned before the spores burst.
5. It is recommended to avoid ratooning of crops affected by the disease.
6. Practicing suitable crop rotations with non-host crops can help in controlling the disease.
7. Planting sugarcane in healthy soil is essential to avoid infection.
8. Where the disease is prevalent, it is advisable to use dry sowing for the crop.
9. Autumn planting of sugarcane should be avoided.
10. Encouraging the use of resistant varieties is recommended to help control the spread of the disease.

References:

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33. Rice Blast and Their Losses

Introduction of Rice:

    Oryza sativa, commonly known as rice, is a crucial staple crop worldwide, particularly in Asia, where it provides a significant source of dietary carbohydrates and calories for roughly half of the global population. In addition to its nutritional value, rice serves as a vital economic crop in many countries, contributing to foreign income through exports. Each year, billions of tons of rice are consumed globally, with billions more being exported to various regions around the world.

• Rice is a grain that comes from either the Oryza sativa (Asian rice) or Oryza glaberrima (African rice) species. 
• There are more than 40,000 different varieties of rice, with Basmati, Thai Jasmine, and Italian Arborio being among the most popular.
• Interestingly, two Japanese car brands were named after rice: Toyota, which translates to "Bountiful Rice Field," and Honda, which means "Main Rice Field."
• Growing rice requires a significant amount of water, with approximately 5,000 liters needed to produce just one kilogram of rice.

1. Rice Blast:

Causal Organism:

    Pyricularia oryzae

Hosts and Symptoms:

    M. grisea is a pathogenic ascomycete fungus that can reproduce both sexually and asexually to produce specialized infectious structures called appressoria. These structures can infect aerial tissues, while hyphae can infect root tissues, making the fungus highly effective as a plant pathogen.

    Rice blast disease has been reported in various rice strains, including M-201, M-202, M-204, M-205, M-103, M-104, S-102, L-204, and Calmochi-101. Among these, M-201 is the most susceptible to infection.

• Leaf Blast: The crop is susceptible to fungal attacks throughout all stages of its growth, with visible signs of infection appearing on its leaves, nodes, rachis, and glumes. Lesions may start as tiny, bluish-green flecks on the leaves, which can expand during periods of high humidity to form spindle-shaped spots with a grey center and a dark brown margin. This symptom is commonly known as "Leaf Blast."

• 
  Nodal Blast: As the disease progresses, the spots on the leaves will merge, resulting in the drying and withering of large areas of the affected leaves. In addition to the leaves, spots may also develop on the sheath, and severe infections can cause the entire nursery or field to appear burnt. The fungus may also cause the formation of black lesions on the nodes, which can girdle and weaken them. This can result in the breakage of the affected nodes and death of the plant parts located above them, a symptom referred to as "nodal blast."
• Neck Blast: As the crop enters the flowering stage, the fungus can also infect the peduncle, causing the appearance of brownish-black lesions. This symptom is commonly referred to as "rotten neck," "neck rot," or "panicle blast" and is sometimes also called "neck blast."

    Early neck infection can result in the failure of grain filling, whereas late disease may only allow partial grain filling to occur. Additionally, small brown to black spots may be visible on the glumes of heavily infected panicles. The fungus can significantly reduce crop yields, with losses ranging from 30 to 61 percent depending on the stage of infection.

Pathogen:

• The mycelium of the fungus is typically hyaline to olivaceous in color and contains multiple septa. 
• Conidia, pyriform to ellipsoid in shape, are produced in clusters on long, septate, olivaceous conidiophores. These conidia have a broad base with a hilum and are typically 3-celled and hyaline to pale olive green in color. 
• The perfect state of the fungus, M. grisea, produces perithecia. The ascospores are hyaline, slightly curved, fusiform, and typically have 4 cells.

Favorable Conditions:

• Rice blast disease is favored by intermittent drizzles, cloudy weather, more rainy days, longer periods of dew, and high relative humidity ranging from 93-99 percent. 
• Additionally, low night temperatures below 26˚C or between 15-20˚C, the availability of collateral hosts, and excessive nitrogen can contribute to the development and spread of the disease. 
• To forecast rice blast disease, a combination of factors must be considered, including a minimum night temperature range of 20-26˚C, a high relative humidity of 90 percent or above, and these conditions lasting for at least one week during any of the three susceptible phases of crop growth: the seedling stage, post-transplanting tillering stage, and neck emergence stage. 
• The first leaf blast forecasting model in Japan was developed and known as BLAST.

Disease Cycle:

    Rice blast disease is primarily spread through airborne conidia, which are present throughout the year. The fungus can also be transmitted through infected straw and seeds, and irrigation water can carry conidia to different fields. Collateral hosts such as Panicum repens, Digitaria marginata, Brachiaria mutica, Leersia hexandra, and Echinochloa crusgalli can also serve as a source of survival for the fungus.

    When spores land on rice leaves, they can germinate, penetrate the leaf, and cause a lesion within four days. The fungus can produce more spores in as little as six days. Infections that result from spores arriving from a distance are known as primary infections, which typically result in a few scattered spots on leaves. However, spores that arise from primary infections can lead to many more infections, a process known as the secondary spread. Secondary spread is responsible for the severe epidemics of rice blast disease in fields and localized areas.

Management:

• To prevent disease in crops, it's recommended to cultivate moderately resistant varieties such as CO47, IR 20, ADT36, ADT39, ASD 18, and IR64, while avoiding highly susceptible varieties like IR50 and TKM6 during disease-prone seasons. 
• It's also important to remove weeds from the field bunds and channels.
• Treating seeds with Captan, Thiram, Carbendazim, Tricyclazole, or Pseudomonas fluorescens at a rate of 2 g/kg can help prevent disease. In the nursery, spraying with Carbendazim (500mg/L) or Tricyclazole (300mg/L) is recommended.
• To protect the main field, it's advisable to spray with Edifenphos (500 ml), Carbendazim (500 g), Tricyclazole (500 g), or Iprobenphos (IBP) (500 ml/ha).

Global Losses:

• Scenario three analysis showed that an average of $69.34 million is lost annually to blasts in the Mid-South of the US, due to yield loss and mitigation costs.
• If the maximum infection rate of 46.95% is applied to susceptible hectares, the potential economic loss is estimated to be $203.49 million annually.
• The calculated potential economic loss as a share of the total value of rice production in Mississippi, Louisiana, and Arkansas is estimated at 3.98%, 4.02%, and 4.92%, respectively.
• The total value of rice production data was obtained from USDA and converted to 2014 dollars using annual CPI retrieved from IMF.
• Overall, the potential economic loss for scenario three is estimated at 4.08% as a share of the total value of rice production in the Mid-South of the US.
• The rice blast caused by Magnaporthe oryzae is a significant threat to global food security, resulting in around 30% of rice production losses worldwide.
• These losses have a direct impact on consumer welfare and increase the global price of rice, which can adversely affect food security.

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32. Role and Importance of Agriculture Sector in Economic Development of Pakistan

 Role and Importance of the Agriculture Sector in the Economic Development of Pakistan

Introduction of Agriculture:

    Agriculture involves cultivating land or soil for the purpose of production, and it plays a crucial role in the development and economy of Pakistan. Nearly half of the labor force, or 48%, is directly involved in agriculture, making it the primary source of income for a significant portion of the population. Additionally, around 70% of the population is connected to agriculture either directly or indirectly. Agriculture serves as a primary source of food for a large segment of the Pakistani population and provides raw materials to the industrial sector. With a contribution to GDP of approximately 25%, agriculture has a greater impact on the economy than any other sector.

As per the Pakistan Economic Survey 2021-22:

• The agriculture sector accounts for 22.7% of the country's GDP.
• The agriculture sector experienced a growth rate of 4.4%.
• The labor force engaged in agriculture comprises 37.4% of the total workforce.
• The total cropped area, which spans 24.1 million hectares, makes up 30.3% of the country's land area.

Role or importance In the Economic Development of Pakistan:

There are following main points in economic development which are given below:

1. Increase in Per Capita Income:

    Per capita income refers to the average annual income of individuals within a nation and is obtained by dividing the national income by the total population. The agricultural sector plays a significant role in providing employment to the unemployed population, thereby contributing to an increase in both individual and national income. Given that the per capita income in Pakistan is $1798 according to the Pakistan Economic Survey 2021-22, the agricultural sector is crucial in driving its growth and improving the living standards of the population.

2. The Major Source of Employment:

    The agriculture sector is a significant source of employment for a major portion of Pakistan's labor force. Directly employing 37.4% of the workforce, it also serves as a crucial source of income for 65% of the rural population. Given its substantial contribution to employment, the agriculture sector plays a vital role in reducing both unemployment and disguised unemployment. Therefore, it can be considered the main sector that provides employment opportunities to a large segment of the Pakistani population.

3. Supply of Food:

    Food is considered the most fundamental of life's basic necessities, and the agricultural sector is responsible for providing a wide range of food items, such as wheat, rice, corn, sugarcane, vegetables, fruits, and more, to the entire population of Pakistan, regardless of their occupations. The agricultural sector also produces food for the animals that provide milk, cheese, butter, and meat, which are necessary for maintaining the health and efficiency of the population. As per the Pakistan Economic Survey 2021-22, the food group exports of Pakistan amount to $1523 million.

4. Supply of Surplus Labor:

    Approximately 60% of Pakistan's population resides in over 61,000 villages. The agriculture sector, which often employs disguised unemployment and farm mechanization, serves as a crucial source of labor for the industrial sector. As a result, an increase in income resulting from the agricultural sector's growth can significantly improve the living standards of people, especially those living in rural areas.

5. Poverty Reduction:

    Agricultural development plays a crucial role in promoting rural development by reducing poverty and stimulating non-farm employment opportunities. When the productivity of the agricultural sector increases, it helps to provide better living standards for people living in rural areas. This includes access to basic necessities such as water supply, sanitation, health services, and educational facilities. However, despite the progress made, a significant portion of Pakistan's population - 29.5% - still lives in poverty, highlighting the need for continued efforts to promote agricultural and rural development to address this issue.

6. Supply of Raw Material:

    The agricultural sector in Pakistan plays a crucial role in not only providing food but also producing a range of raw materials such as cotton, sugarcane, tobacco, rice, oil seeds, meat, and milk. These raw materials are supplied to various agro-based, small-scale, and large-scale industries in the country, serving as critical input for their production processes. As such, the agricultural sector serves as a significant source of raw materials for the various major industries in Pakistan, contributing to the country's overall economic growth and development.

7. Development of the Industrial Sector:

    The agricultural and industrial sectors in Pakistan are strongly interdependent and play a crucial role in each other's development. When agricultural productivity increases, it leads to a rise in farmers' income. This, in turn, increases the demand for agricultural goods, such as tractors, fertilizers, pesticides, tube wells, etc., and industrial goods like televisions, mobile phones, and computers. As a result, the industrial sector experiences growth, contributing to the overall development of the economy. According to the Pakistan Economic Survey 2021-22, the growth rate of the industrial sector in Pakistan is 7.2%.

8. Improvement in Living Standards:

    The development of the agricultural sector in Pakistan has the potential to increase the income of farmers, enabling them to improve their living standards. With an increase in income, farmers can invest in constructing better houses and purchase luxuries such as televisions, computers, mobile phones, motorcycles, and other items that improve their quality of life. Thus, the growth of the agricultural sector has a direct impact on the standard of living of the population, particularly in rural areas where agriculture is a major source of income.

9. Economic Development:

    The agricultural sector plays a crucial role in the economic development, progress, and prosperity of Pakistan. It not only provides employment opportunities to a large segment of the population but also produces exportable items, which increases the foreign exchange resources. As a result, the growth of the agricultural sector is essential to achieve rapid economic development. In fact, the real GDP growth rate of Pakistan's economy is 6.0%, which underscores the importance of the agricultural sector in driving economic growth and development.

10. Increase in Government Revenues:

    While there is no direct tax on agricultural income in Pakistan, the government indirectly receives a substantial amount of tax revenue from the agricultural sector. This is achieved through the imposition of duties on imported technologies used in farming, taxes on chemicals and other inputs used in agriculture, and other indirect taxes that are levied on the sector. Thus, while the agricultural sector is a vital source of income and livelihood for many people, it is also an important source of revenue for the government.

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