Monday 18 February 2013


Phomopsis Seed decay:




     Phomopsis seed rot occurs when harvest is delayed due to rainy, wet weather. Seed infection may reduce seed quality, vigor, and viability. Severely diseased seeds appear moldy and may be graded lower, which leads to dockage at the elevator. Planting diseased, poor-quality beans will result in reduced stands that may reduce yields. Pod and stem blight also occurs when soybeans mature during wet weather and harvest is delayed. These soybeans may be caused by a number of different fungi in the Diaporthe-Phomopsis complex. Phomopsis seed decay is caused primarily by Phomopsis longicolla, but other Diaporthe/Phomopsis spp. also can cause seed decay.

     Severely infected seeds are shriveled, elongated, and cracked and appear white and chalky. Seeds also may be infected and not show symptoms. Affected seeds usually do not germinate or are slow to germinate. Seed infection may cause pre- and post emergence dampening-off, and under severe conditions, stands can be reduced enough to lower yield.

   Symptoms of Phomopsis seed rot, pod and stem blight are readily apparent after the plants reach physiological maturity. Dead petioles, stems, and pods may be covered with small black specks, which are the fruiting bodies of the fungus (pycnidia). The pycnidia are usually arranged in parallel rows along the stem. During less favorable weather conditions, pycnidia may be confined to small areas of the stem near the soil surface or around the lower nodes of the stem. Pycnidia are also found scattered on discolored, poorly developed pods. Seeds that are infected have a range of symptoms from none to severe. Affected seed are usually cracked, shriveled, and covered with white mold. These severely infected seeds rarely germinate when planted. Less severely infected seed may germinate, but seedlings may show signs of seedling blight. Seedlings developing from moldy seed may have brown to reddish colored lesions on the cotyledons, or reddish-brown streaks may develop on the stem at or below the soil surface.

      Infested crop debris and soil are the major sources of primary inoculum. However, diseased seeds are an important factor in the long-range dissemination of the pathogen. Seed infection tends to be more severe when harvest is delayed, when early-maturing cultivars are grown, or when crops are grown in regions where warm; humid weather prevails at harvest time. More seed decay occurs in plants that are deficient in potassium, infected with one or more viruses, such as soybean mosaic poly virus, or heavily attacked by insects.

Thursday 14 February 2013


Fruit & Vegetables in Europe:

     
      The fruit and vegetable market is taken to be the sale to consumers of fresh fruit and fresh vegetables, including potatoes. Volumes are calculated from per capital availability and mid-year populations, where 'availability' denotes the quantities sold (or otherwise available) to consumers without regard to whether the produce is physically consumed or not. Values are calculated from the total volume consumed and the retail price per kg. Processed and preserved fruit and vegetables, including juices, frozen and canned products, are excluded. All currency conversions are calculated using constant average annual exchange rates.
For the purpose of this report the global figure is deemed to comprise of the Americas, Asia-Pacific and Europe.
The Americas comprises Argentina, Brazil, Canada, Chile, Colombia, Mexico, Venezuela, and the US.
Europe comprises Belgium, the Czech Republic, Denmark, France, Germany, Hungary, Italy, Netherlands, Norway, Poland, Romania, Russia, Spain, Sweden, the Ukraine and the United Kingdom.
Asia-Pacific comprises Australia, China, Japan, India, Singapore, South Korea and Taiwan.


Research Highlights

The European fruit & vegetables market generated total revenues of $187.4 billion in 2008, representing a compound annual growth rate (CAGR) of 5.4% for the period spanning 2004-2008.
Vegetables & potatoes sales proved the most lucrative for the European fruit & vegetables market in 2008, generating total revenues of $110 billion tones, equivalent to 58.7% of the market's overall value.
The performance of the market is forecast to accelerate, with an anticipated CAGR of 5.6% for the five-year period 2008-2013, which is expected to drive the market to a value of $246.2 billion by the end of 2013.


Market Analysis

The European fruit & vegetables market has been growing at a fairly strong but fluctuating rate and this trend is forecast to continue in a similar fashion with more stabilized growth rates over the years up to 2013.
The European fruit & vegetables market generated total revenues of $187.4 billion in 2008, representing a compound annual growth rate (CAGR) of 5.4% for the period spanning 2004-2008. In comparison, the German and UK markets grew with CAGRs of 6.1% and 4.9% respectively, over the same period, to reach respective values of $27.1 billion and $18.3 billion in 2008.
Market consumption volumes increased with a CAGR of 1.8% between 2004-2008, to reach a total of 70.2 million tonnes in 2008. The market's volume is expected to rise to 78.3 million tonnes by the end of 2013, representing a CAGR of 2.2% for the 2008- 2013 period.
Vegetables & potatoes sales proved the most lucrative for the European fruit & vegetables market in 2008, generating total revenues of $110 billion tones, equivalent to 58.7% of the market's overall value. In comparison, sales of fruit generated revenues of $77.4 billion tones in 2008, equating to the remaining 41.3% of the market's aggregate revenues.
The performance of the market is forecast to accelerate, with an anticipated CAGR of 5.6% for the five-year period 2008-2013, which is expected to drive the market to a value of $246.2 billion by the end of 2013. Comparatively, the German and UK markets will grow with CAGRs of 6.0% and 3.8% respectively, over the same period, to reach respective values of $36.2 billion and $22 billion in 2013.

Wednesday 13 February 2013


Downy Mildew:

       Downy mildew is a widespread, serious disease of beans, crucifers, cucurbits, maize, potato, tomato, rice but most common with grapevines. Previously considered a fungus, the downy mildew pathogen called Plasmopara viticola, is now classified an algae. Initial leaf symptoms are light green to yellow spots, called “oil spots” because they may appear greasy. Under humid conditions, white, downy spore masses can be seen on the lower leaf surface. These spores are wind dispersed. The lesions eventually turn brown as the infected tissue dies. Severely infected leaves drop prematurely, which can reduce winter hardiness of the vine. Infected flower clusters dry up or become covered with white spores under humid conditions. Infected berries turn a mottled dull-green or reddish purple and readily fall from the cluster. Although berries become resistant to infection within three weeks after bloom, the rachis remains susceptible for several weeks longer.

     Downy mildew needs warmth and water. As for most algae, in most stages of its life cycle, take away water and it will die. As a reminder of its dependence on free-water and because water runs downhill, think of downy as ‘down-hill mildew’! In contrast, we may call the other mildew ‘powdery-dry’ mildew because it grows in the absence of free water. Periods of high risk from downy can be determined by monitoring the vineyard microclimate for factors such as temperature, rainfall, relative humidity (RH) and leaf wetness. This allows optimum timing of control actions when they are needed, and gives confidence to withhold sprays when not required. Affected leaves turn yellow and are rapidly shed from the plant. A fine white fungal growth may be visible on the lower leaf surface, but affected leaves decay rapidly. Flowers are also commonly shed, and the plant is often reduced to bare branches with a small tuft of yellow leaves and flower buds at the tip. Severely affected plants will eventually die

      Spreads in warm moist weather Downy Mildew begins with primary infection when spores are splashed from the soil to the leaves. Downy mildew spreads in secondary infection when spores are splashed from leaf to leaf to bunch.

     A useful rule of thumb is the three t’s of good spray application: type, timing and technique. Like three links in a chain, each of the t’s must be of good quality for good management of disease. We shall discuss the first two here. The third, technique, includes spray coverage and dose. Fungicide Types: the two main types of downy mildew fungicide are classified according to their timing in relation to infection events. They are best applied when they are most effective, that is either pre- or post-infection. Downy mildew can be avoided by rotating annual flowers and vegetables and by avoiding overwatering, overcrowding, and poorly drained soil. Other avoidance measures are growing resistant varieties, sowing disease-free seed, removing diseased parts and crop refuse, eliminating weeds, and maintaining balanced soil fertility. The application of copper, maneb, or zineb is effective against many downy mildews, but the amount of residue on vegetables must be considered.

Tuesday 12 February 2013


Potato & Diseases - Part II:

Black Dot
    Research on black dot over the past few years has shed new light on many aspects of this fungal disease. Black dot is a difficult disease to control and there is no one silver bullet to knock it out

Symptoms:The name "black dot" accurately describes the numerous dot-like, black sclerotia that can appear on tubers, stolons, roots, and stems both above and below ground level. A significant portion of the stem may be covered with sclerotia which are easily seen after vine kill. Total root growth is reduced and appears brown to black in color. Sclerotial bodies can be found on both roots and stolons. Some of the roots and stolons appear white in this photograph because the cortical tissue has been sloughed off due to severe infection. Apparently, enzymes secreted by the pathogen are responsible for the foot and root rot stages. Small, brownish lesions caused by Colletotrichum, bearing a resemblance to Rhizoctonia-induced lesions, may appear on recently infected stolons.

     Tuber infection appears as brownish to gray discoloration over a large portion of the tuber, or as roundish spots often larger than 1/4-inch in diameter. Silver scurf can also appear as patchy discoloration on the tuber surface, but takes on a silvery sheen when the affected area is moistened. Both pathogens frequently occur on the same tuber.

Control:

Seed: Purchase certified seed potatoes, since seed is the only way known to infest a clean field. There are no resistant potato cultivars, thin-skinned cultivars are more susceptible. Do not sterilize the seed.
Field: Use long rotations of 3-4 years. Keep the field free from debris, soil adequately fertilized, avoid excess water but keep the field well irrigated. Avoid skinning and bruising the tuber at the time of harvest. Note – there are no chemical control measures for black spot.
Control solanaceous weeds (ex: black nightshade)
Rotate with non-host crops (ex: tomatoes).

Powdery Scab

Symptoms: Tubers are typically raised pustules with a powdery mass. Spore balls, which are found in these lesions, can be seen with the aid of a microscope. Seeing the spore balls is the one sure way to identify the presence of powdery scab. Root galls will increase throughout the season. It a tuber has "pimples," set is aside for 24 hours. The color will change if the lesion is powdery scab.

    Symptoms can develop after harvest. Tuber to tuber spread in storage has never been documented. Contamination of seed pieces with spore balls is possible, however. Infected tubers may shrink in storage.

Control:

    There is no good control for powdery scab. Control measures need to both reduce the inoculum level in the soil and the inoculum level on the seed. Spores can be spread by contaminated seed tubers or by contaminated soil. Mancozeb-containing seed treatments may help reduce the spread of the pathogen from infected seed.

Gray Mold

     Gray mold originates primarily from infection of wounds such as punctures and bruises that are created at harvest and during the postharvest handling process. The decayed area appears light brown to dark brown and color is similar across the decayed area. The decayed area is spongy, and diseased tissue is not separable from the healthy tissue, which is different from blue mold (a soft decay)

Sclerotinia Stalk Rot (White Mold)

Control:
     Protectant fungicides may be applied to prevent gray mold developing on foliage
High levels of K and N are reported to reduce the percentage of tuber infection. Avoid mechanical damage during harvest.
If tubers are damaged during harvest operations, permit tubers to wound heal prior to low temperature storage.
Remove as much excess soil and stem material from potatoes during harvesting as possible.
Store potatoes at 40 degree Celcius.

Thursday 7 February 2013


Pollination Management:


        Pollination is a keystone process in both human managed and natural terrestrial ecosystems. It is critical for food production and human livelihoods, and directly links wild ecosystems with agricultural production systems. Pollinators are an element of crop associated biodiversity, and provide an essential ecosystem service to both natural and agricultural ecosystems. In the case of agricultural ecosystems, pollinators and pollination can be managed to maximize or improve crop quality and yield. Pollination depends to a large extent on the symbiosis between species, the pollinated and the pollinator, and often is the result of intricate relationships between plant and animal - the reduction or loss of either affecting the survival of both. The vast majority of flowering plant species only produce seeds if animal pollinators move pollen from the anthers to the stigmas of their flowers. Without this service, many interconnected species and processes functioning within an ecosystem would collapse. Many plants are wind pollinated, while animal pollinators include bees, and to a lesser extent butterflies, moths, flies, beetles and vertebrates.

      At least one-third of the world’s agricultural crops depend upon pollination provided by insects and other animals. As farm fields have become larger, and the use of agricultural chemicals increases, mounting evidence points to a potentially serious decline in pollinators. In Asia, the domesticated honeybee, Apis mellifera have been utilized to provide managed pollination systems, but for many crops, honeybees are either not effective or are optimal pollinators. The process of securing effective pollinators to service agricultural fields is not always easy, and there is a renewed interest in ensuring pollination services through practices that support wild pollinators.

     In order for society to be able to capitalize upon the value of bees in pollination and environmental monitoring, a variety of solutions to the taxonomic impediment will be required. Bees are essential components of almost all of the world’s terrestrial ecosystems. They provide both pollination services, and are excellent indicators of the state of terrestrial environments including responses to global warming. A major challenge to knowing how to manage wild bees for pollination services, or to using their occurrence as an indicator of ecosystem health is the taxonomic impediment to identifying the exact name of a pollinator.


     A decline in pollinator populations also affects plant biodiversity. Native pollinator species may decrease when their nesting habitats are destroyed, when they find less wild flowering plants to forage on throughout their life cycle, and when they are impacted by injudicious use of pesticides.


Friday 1 February 2013

The Role of Biotechnology in Seed Production:


  For centuries farmers across the globe have been experimenting with plants by using conventional plant breeding techniques to obtain better quality of seeds and hence better yield. With the understanding of the biology behind trait inheritance this process became more scientific and the advancement of biotechnology in the past two decades has revolutionized the same to produce high quality seeds.
   Biotechnology in simple terms is the science of engineering the genetic make up of any organism to achieve desired traits in the organism. The basis of improved seed production can depend broadly on factors like new or improved traits, resistance to disease, stress tolerance, etc. To achieve any these goals biotechnology offers various techniques that can be classified under the following:
  • Tissue Culture
  • Genetic Engineering
     Tissue culture is an in-vitro aseptic technique for growing and multiplying plant tissues in a controlled environment. Plant breeders produce the F1 hybrids which are heterotrophic. But further to maintain a uniform genotype, self pollination of the seed producing plant should be prevented. Micro propagation of these F1 hybrids eliminates the need for manual emasculation for sterility or pollination and enables rapid multiplication. For example, in the case of hybrid tomatoes, Murashige and Skoog medium (MS) was used to propagate the shoot tip of the F1 hybrid. The parent ex-plants and the auxiliary buds grown are sub-cultured on the same media each giving rise to seedlings ready for transplantation. The results achieved by this method were highly efficient as the pro-genies contained all heterogeneous traits of the hybrid explants. The uniformity of the genotype was also not compromised. Production of hybrid seeds by using this technique had reduced the time period of multiplication by three folds. This method is cost effective, less labor intensive, and rapid.

    Similarly micro-propagation can also be used for maintaining cell lines of male sterility of dominant and recessive genes and self-incompatible cell lines. Self incompatibility is crucial in preventing self pollination. Another tissue culture technique used for the development of self incompatible cell lines is anther culture.

    Anther culture:Self incompatible lines are developed by culturing the microspores of the F1 hybrid which produce haploid seedlings. Chromosome doubling of the haploid F1 hybrid results in true breeding homozygous lines. This technique is mainly used for vegetative plants like tubers and Cole crop.