Diseases following fresh rainy spell

The Met Office on Tuesday advised farmers to ensure field sanitation and prophylactic fungicidal sprays to safeguard the standing crops from diseases following the fresh rainy spell. "Weeds are expected to shoot in excess after the rains. Farmers should control weeds growth soon after the rains," the office said in its 10-day advisory for farmers.
It said the farmers should halt irrigating their crops since the continuing rainy spell provided sufficient water and asked the growers to plan irrigation keeping in view the likely rain in agricultural plains of the country. "Wheat crop is growing at Heading/Flowering/Milk Maturity stages in most of the agricultural plains of the country," it said, adding that farmers should step up to control further weeds growth to prevent negative impact on their crops. "Weeds removing practices should be started soon after expected rains in the mentioned areas," the office said.
It says wheat crop is growing at very crucial development stages of milk maturity/ wax maturity, in Sindh and Punjab province. "Farmers of these areas are advised to irrigate the crops as per requirement keeping expected rains in mind," it adds. Rainfall/ light snowfall over the hills and over upper and central parts of Punjab is expected in the next 10 days. It forecast rainfall for Sindh at isolated places during first five days of the advisory while dry weather is likely to prevail in its most parts till March 20.
It said rainfall/light snowfall over the hills and over upper and central parts of Khyber Pakhtunkhwa is expected during the period. Rainfall is expected at isolated places of Balochistan during the first five days of the forecast period. In Gilgit-Baltistan, it said mainly cold and cloudy weather is expected in most parts. However, light to moderate rainfall (with snow over the hills) expected at isolated places during the period. In Kashmir, the office said cold and cloudy weather with rainfall/light snowfall over hills is expected in most parts.

Source: Business Recorder 

Common Rose Diseases

By Marie Iannotti, About.com Guide

Despite the best efforts to keep roses disease free, there will inevitably be period problems to deal with. Keep tabs on your rose bushes so that you can remedy the situation before it gets out of hand. Be sure to accurately identify the problem before reaching for a spray and start with the least toxic solution.

1. Black Spot: Black spot is a fungus that is very common during humid weather because it is a water-bourne disease. As its name implies, small black spots form on leaves and stems, eventually causing the leaves to drop and weakening the plant.
   Treatment: Choose black spot resistant varieties and be meticulous about sanitation. Water the roots of the rose, avoiding the foliage. Water in the morning, so that splashed leaves have time to dry off. If Black Spot is an annual problem, try a dormant spray of lime sulfur at the end of the season and again in early summer. Once Black Spot appears, it is hard to stop. Neem oil and Sprays containing Potassium bicarbonate are somewhat effective.
2. Downy Mildew: Downy mildew is a very serious disease that spreads rapidly and can defoliate a rose plant in days. It is not as common as Black Spot and favors cool, wet weather. Purple spots with yellow edges form , often on the veins on the top side of the leaves and along the stems. Pale gray fuzz can form on the under side of the leaves. The leaves will eventually become brittle and fall.
   Treatment: The good news is that Downy Mildew often clears up with the weather. To reduce the chance of Downy Mildew, practice good garden sanitation and keep the rose plants well pruned for air circulation. As with other diseases, a dormant spray may help.
3. Rust: A Rust infection is easy to spot. Small orange pustules spots form on the undersides of the leaves. This fungus can also cause defoliation. Rust is most prevalent when nights are cool.
   Treatment: Treatment of Rust is similar to treatment of Black Spot, above: Good sanitation and a preventative dormant spray after pruning. Once infected, remove all infected leaves and try Neem oil for control.
4. Mosaic Virus: Once a rose is infected with Rose Mosaic Virus, there’s not much to be done except check with the nursery for a replacement. Rose Mosaic Virus shows up as yellow mottling on leaves and deformed new growth. It can stunt growth or it can be a mild infection. If there are only a few affected leaves, the plant may continue growing and blooming fine. The really good news is that it won’t spread to your other roses.

Source:

Black Spot Fungal Disease Overview

Although this fungal blight can infect many types of plants, including apple trees, tomatoes, and more, it is most often associated with roses. It’s the rose gardener’s most dreaded foe.

Host Plants

Any type of rose can become infected with black spot. Some species have been bred to be resistant to this fungus, but most of the thousands of rose species have not. Other plants related to roses, such as apples, may also be hosts – some may not show much of an infestation, in fact, and can act mainly as carriers instead.

Symptoms on Roses

The symptoms are straight-forward and well-known amongst rose gardeners. It generally manifests first on the leaves of the rose bush. It will then quickly spread, usually via water dripping from leaf-to-leaf or from leaf shaking from a breeze or animal. It quickly infests the plant’s leaves and their stems, reaching eventually for the flowers themselves. The first sign is usually a dark gray or black spot on the leaf’s underside wherever moisture might collect. It will then spread in patches across the leaf, eventually eating through it.

Life Cycle

Like most fungi, black spot needs warmth, moisture, and shade from the sun. This is usually found on the underside of leaves and inside the flowers. The fungus spreads most often through soil contamination and falling leaves and petals that have been infected. Spores will lie dormant in the ground until spring.

How This Fungal Disease Impacts the Plant

Black spot will kill leaves and, worse, destroy the roses themselves. At the very least, it will make the plant and flowers ugly and non-presentable. It can eventually kill the rose plant if it begins early enough in the season.

How to Prevent

As with most fungal infections, prevention is worth a pound of cure with black spot. Planting roses in a well-aerated spot where they receive light breezes and good air flow is a must. Proper care of the soil around them, including choosing mulches that are unable to carry black spot, is also important. Watering from the root rather than with a sprinkler system is a good idea as well. Keeping infected plants quarantined from others is vital. Many gardeners will destroy one rose bush that’s been infected in order to save the rest from possible infection. Destruction should be through bagging, removing, and burning the plant. Never compost an infected plant of any type.

Treatment of Black Spot

Less extreme treatments include fungicides, which have a high rate of success in most areas. Many of these must be hand-applied as a spray or powder. Apply before roses bud, if at all possible, but anytime the black spot has appeared is a good time. The disease’s treatment is more important than the aesthetics of the plant. Heat lamps, large fans, and other options have also been tried with limited success. The idea is to destroy the climate that the fungus thrives in.

Resources:

http://web.extension.illinois.edu/cfiv/homeowners/000805.htmlhttp://www.aaes.auburn.edu/comm/pubs/highlightsonline/summer96/blackspot.htm

Source: http://www.gardeningchannel.com

Cultural Methods of Vegetable Disease Control

Most vegetables are susceptible to one or more diseases. You can, therefore, anticipate disease problems sooner or later in your vegetable garden. By following good cultural practices and taking preventive measures, your chances of garden failure due to disease problems can be reduced.

Garden site selection is important to pro-duce high yields of healthy vegetables. Trying to grow vegetables on a poor site is one of the main causes of garden failure. Although few people will have ideal garden sites, they should select the best site available.

Garden sites should not be within the drip line of large trees. Avoid planting near black walnut trees, since they produce a root sub-stance that is toxic to certain vegetables, especially tomatoes. The garden site should be slightly sloped to provide good water and air drainage through the soil.

Excess soil moisture can damage vegetable roots, as well as promote root diseases caused by certain fungi. Air movement through the garden is also important to help dry the foliage, thus reducing the chances of fungal and bacterial infections. Garden sites with good air drainage are less likely to be damaged by late frosts.

Most garden vegetables require full sunlight for maximum production. Sunlight also hastens drying of foliage. Soil tillage should be done early enough, prior to planting, to allow decomposition of raw organic matter such as manure or green plant material. This usually requires about six weeks under warm temperatures and longer at low temperatures. Organic material that has not decomposed can be a source of disease organisms and can also promote development of certain diseases such as root and stem rots. Applying nitrogen fertilizer before plowing or tilling green plant material into the soil will hasten its de-composition.

Crop rotation will help prevent the buildup of disease-causing organisms in the soil. Some disease causing organisms affect one vegetable or group of vegetables, but may not affect an-other. Several vegetables of the same family, such as squash, cucumbers and cantaloupes, may be affected by the same disease. Therefore, it is not a good practice to grow plants of the same family in rotation. Table 1 gives crop groupings for rotation to control soil-borne diseases. At least a three-year rotation is suggested for vegetable crops.

Sanitation is very important in controlling vegetable diseases. Many disease-causing organ-isms survive the winter in plant debris, cull fruit or plant stubble left in the garden. Any practice that will eliminate these overwintering sites for fungi, bacteria, viruses and nematodes will reduce the occurrence of disease problems the following year. Removal or plowing-under of crop stubble and trash helps destroy overwintering populations of disease organisms. Some disease-causing organisms are able to survive the off season on contaminated equipment or containers. Equipment that has been used in disease-infested vegetable gardens or containers used in handling diseased vegetables should be disinfested before being used again.

Disease-free seed and transplants are a must in vegetable production. Seed should not be saved from diseased plants. Always buy seed from a reputable dealer, since you normally cannot tell from their external appearance if seed are contaminated with disease-causing organisms.

Certain geographical areas, such as the arid western states, can produce disease-free seed because of climatic conditions. Seed from these areas should be stipulated in your seed orders. Gardeners starting their crop from transplants should, likewise, insist on disease-free plants.

Seed treatments vary, depending on the crop as well as the disease to be controlled. Some disease-causing organisms are carried on the surface of seed and can be controlled by a simple fungicide treatment. Fungicides are not effective against those organisms carried beneath the seed coat.

Fungicides applied to seed also give young seedlings some protection from soil-borne disease organisms as they germinate and emerge. Such treatments, however, do not control organisms that attack the plant after the seedling stage.

A seed treatment is usually applied by the company from which the seed is purchased. Home-grown seed can be treated at home with relative ease. Thiram or Captan fungicides can be used as seed treatments on most vegetable crops. Use these protectant fungicides according to instructions on the label. For small quantities of seed, such as packets, apply sufficient fungicide to coat the seed surface. Simply place a small quantity (comparable to the size of a match head) in the packet, reclose and shake to coat the seed with the fungicide.

Planting dates can be an effective tool in reducing diseases of vegetables. Okra, for in-stance, requires warm soil for good germination and growth. If planted when the soil is still cold, the seeds will rot, or if they do germinate, they will probably develop damping-off or stem rot. Some crops, such as corn and beans, should be planted as early as the weather permits to escape severe virus infections. Aphids that transmit viruses are usually at lower population levels early in the season.

Mulches can be used to conserve moisture, keep fruit clean and prevent diseases. Mulches reduce fruit rot on crops, such as strawberries, tomatoes, squash, cucumbers and melons by preventing direct contact with the soil. Mulching will reduce splashing of soil onto lower fruit and foliage by rain.

Staking or trellising tomatoes, pole or half runner beans and cucumbers will prevent soil contact with the foliage and fruit. Air circulation will be better if these plants are trellised, thus promoting better drying of foliage and reducing diseases. Pesticides can be more effectively applied to trellised plants.

Watering can influence the development and severity of many foliage diseases. Wet foliage is favorable for the development of most diseases. To reduce infections, apply irrigation water to the soil rather than the foliage. If water must be applied to the foliage, then it should be done in late morning or mid-afternoon to allow the foliage to dry before evening.

Maintaining uniform soil moisture can re-duce problems such as blossom end rot of pe-pers and tomatoes. Excessive soil moisture can result in increased root and stem rot diseases. It is best to work in the garden when the foliage is dry to reduce disease spread. Bacterial diseases of tomatoes, beans and other crops are readily spread on hands and clothing of workers when the foliage is wet.

Use of resistant varieties is one of the most economical ways of controlling vegetable diseases. Resistant varieties should be used in areas where diseases are present or where the soil is known to be infested with disease-causing organisms. Resistant varieties should be used even when rotation is practiced.