Crown Rot Identification And Tips For Treatment

Crown Rot is caused by the Phytophthora fungus, which attacks the roots and, most notably, the crown of African Violets. African Violets are most susceptible to Crown Rot when allowed to sit in soil that is heavy and soggy. In almost all cases, Crown Rot is fatal. The best control for Crown Rot is, therefore, prevention.

Distinguishing Symptoms

• Crown is mushy. It may appear translucent brown with a soft, jelly-like consistency.
• Crown darkens. It appears brown or black in color. 

These symptoms indicate that the crown is rotting. If your African Violet has these symptoms, it probably has Crown Rot.

Other Symptoms

• Crown has a weblike substance on it. (Note: This substance should not be confused with the web left behind by Spider Mites, which clings to the flowers and plant hairs of the leaves. Nor should it be confused with the "cotton" specks which characterize Leaf Mealy Bugs.)
• Leaves have a weblike substance on them.
• Leaves darken. They appear brown or black in color.
• Leaves wilt. They may appear translucent brown with a soft, jelly-like consistency.
• Plant growth is slow. 

BIOLOGY

Phytophthora species are soil-inhabiting pathogens that are favored by wet conditions. Although previously considered fungi, Phytophthora species are now considered to be in a separate classification called oomycetes. Species of Phytophthora produce resting spores that survive for years in moist soil in the absence of a suitable host. However, if the soil is completely dried out, these spores are less likely to survive for more than a few months. When a host is nearby and free water (water in soil pore spaces) is present in the soil, resting spores germinate to produce motile spores that can directly penetrate roots, branches, or crowns as long as free water is present. Wounds are not required for infection. Resting spores, decaying host tissue in the soil, and active cankers (disease-infected dead, sunken lesions in plant parts) can all be sources for new infections. The pathogen can be spread in splashing rain or irrigation water, in surface irrigation, and runoff water, and by movement of contaminated soil, equipment, or plant parts. Flooded and saturated soil favors the spread of Phytophthora to healthy plants.Some Phytophthora species are favored by warm weather, some by cool weather. Root rots of avocado, citrus, and tomato are favored by warm conditions, developing most extensively in late spring and early summer. Decay of crown, trunk, and branches of other tree species are favored by cool, wet conditions. These decays develop most rapidly in late fall and early spring.

Treatment

The most important factor in reducing the threat of Phytophthora rot is good water management. Avoid prolonged saturation of the soil or standing water around the base of trees or other susceptible plants. Irrigate only as much and as often as necessary; in an orchard, keep track of the soil moisture around each tree and water only when necessary. If you irrigate trees with sprinklers, use low-angle sprinkler heads and splitters to avoid wetting the trunk and lower branches. If using a drip system, place the emitters at least a foot away from the trunk. Avoid planting susceptible species on poorly drained or shallow soils. Water stress and/or salinity make some plant species more susceptible to infection when wetted subsequently by irrigation or rains.For all vegetable and orchard plants, provide good soil drainage. Good soil drainage is best provided before planting. Drainage should be plentiful to the rooting depth of the plants, generally 3 to 6 feet for trees, 2 to 4 feet for shrubs, and 1 to 2 feet for bedding plants. During favorable weather you do not want the roots and crown of a plant to remain wet for the 4 to 8 hours that are required for Phytophthora to infect the plant.Provide adequate drainage by breaking through soil compaction and hardpan. In poorly drained soils, or in an area where you know Phytophthora is present, consider planting trees and shrubs on mounds. The mounds should be 8 to 10 inches high. Planting depth after settling should be no deeper than as received from the nursery, with the upper roots near the soil level and the graft union well above the soil line. Do not install irrigated turf around the base of trees, remove all weeds, and do not water the crown area directly. Never cover the graft union with soil or mulch. If you are not sure where the graft union is, ask someone at the nursery to show you and mark it. Raised beds provide good drainage in vegetable garden situations also. Group plants according to their irrigation needs. Separate those needing frequent, light irrigations, such as potatoes and strawberries, from those needing infrequent, deep irrigations, such as tomatoes and melons. At the first signs of aboveground symptoms, examine the tree at the soil line for crown rot. Carefully cut away bark that looks affected. If crown rot is present, trees can sometimes be saved by removing soil from the base of the tree down to the top of the main roots and allowing the crown tissue to dry out.

Sanitation

It may be possible to slow the spread of Phytophthora within an orchard by avoiding movement of infested soil, water, and plant parts from an area where Phytophthora rot has developed. Surface and subsurface drainage water and anything that can move moist soil can carry the pathogen to a new area, including boots, car tires, and tools. If the physical setting allows drainage water to flow from infested to uninfected areas within the garden during wet weather, consider putting in drains to channel the water away from healthy plants.

Selection of planting stock

Plant only certified nursery stock from a reputable source, and choose the most resistant rootstocks or varieties available for your area. Less susceptible rootstocks or varieties are available for almonds and stone fruit, apples, cauliflower, and strawberries. Carefully select individual plants that are free of symptoms and/or that come from healthy lots of material.

RotationIf tomatoes have been affected by Phytophthora root rot, avoid planting tomatoes or other susceptible plants such as eggplant or peppers in the same soil for at least one or two seasons. Plant a resistant crop such as corn instead, or leave the soil unplanted and do not irrigate, but keep it well worked to allow the soil to dry as deeply as possible. Different species of Phytophthora attack beans and cole crops, so these plants can be substituted as well. Consult a nursery or farm advisor for possible alternatives in your area.

Chemical control

The most effective way of preventing Phytophthora rot diseases is to provide good drainage and to practice good water management. Along with the appropriate cultural controls, the fungicide fosetyl-al (Aliette) may be used on a number of ornamental plant species to help prevent Phytophthora infections. When applied as a foliar spray it is absorbed by foliage and moves into roots. However, do not rely on fungicide applications alone to control root and crown rot diseases.

Prevention

Prevention is always your best bet for successfully controlling Crown Rot. By adhering to the following guidelines, you will give your African Violets the best chance for eliminating any threat of Crown Rot.

Do not overwater. This is the greatest danger to African Violets. Overwatering leaves the soil soggy, a condition that is ripe for the development of Crown Rot. Water just enough to keep the soil damp. Always allow any excess water to drain. If you are using a self-watering device, which employs capillary wicking, make sure the pot is not in direct contact with the water. Also, it is strongly recommended that you only use wicks supplied by the manufacturer of the watering device.

Do not let the soil dry out completely before watering. Repeated, sudden changes in the availability of water can cause the same effects as overwatering.

Do not use a pot size that is larger than what your African Violet needs to form a tight rootball. If the pot size is too large, your Violet will not be able to absorb all the water, leaving the plant susceptible to the soggy conditions in which 

Crown Rot thrives.

Make sure the pot you use provides adequate drainage. If you are using a plastic pot which has no holes, you can easily add holes yourself with a soldering iron or by simply heating up a screwdriver and pushing it through the bottom of the pot. If you are using a terra cotta pot which has no holes, you can add holes with a drill. For 4-inch pots, use a 1/8-1/4 inch bit and drill from the bottom. Do not press too hard. Go slowly and let the drill do the work.

Use a light, porous potting soil. An ideal potting soil will consist of block-harvested, sphagnum peat moss. Such a potting soil allows any excess water to drain away from the roots. Be sure to pasteurize your potting soil.

Maintain good air circulation around your plants. Keep your growing area clean, and remove spent flowers and leaves as you find them.

Finally, you should strongly consider using a recommended self-watering device. Such devices use capillary action to draw the right amount of water into the soil. This prevents both overwatering and underwatering. For miniatures, there is the MiniWell (fits 1-inch pots) and the Optimara WaterShip (fits 2-inch pots). For larger African Violets, there is the MaxiWell (fits 4-inch pots) and the Watermaid (fits various sizes up to 6 inches.) Each of these self-watering devices is available at a number of hardware and discount stores. In addition, they can also be ordered online from the Selective Gardener, a mail order supplier that specializes in plant care products for African Violets.

Important Note on the Use of Pesticides

Please note that almost all pesticides are formulated for specific uses and conditions. When applied incorrectly, pesticides can cause ill health or damage to plants. Therefore, when using any kind of pesticide or chemical treatment, 

always apply as indicated on the product label.

Seed Germination

For seeds to germinate is not an exact science, but a few general knowledge of science helps to get off seed to a good start.

Water, air, light

Seed should be moist to germinate. During planting, water the seedbed planting the seeds to the depth set on the seed packet, and then enter the soil lightly and water the bed.

According to an article in the growth of the market, most vegetables (as opposed to flowers) is whether or not they light or darkness when germinate. Celery and lettuce do better with more light, so sown on the surface with a very light covering of soil.

Seed should germinate oxygen to so do not let them drown in too much water. Well drained soil will help prevent. Organic matter in the soil will help the soil is well drained and also crusting. Crusted soil is difficult for seeds.

Watering after sowing and must face regularly. Seeds should always damp. Spray the seeds with a fine mist will reduce soil disturbance.

Soaking

Seeds soaked before planting. It helps seeds absorb all the water they need. After the week seeds will have a smaller amount of water needed to maintain their moisture level. This pre-soaking works better for large seeds and less likely to clump together when pre-soaked. Small seeds can drained and mixed with dry materials such as coffee grounds or oatmeal reduces the clumping.

Soak the seeds overnight as they grow seeds such as beans and peas. Week smaller seeds for a shorter time. Seeds should not be so long that the soaked seed skin splits. They will lose nutrients and more vulnerable to disease attacks.

Pre-sprouting

Seeds sprouted before they go into the ground. The benefits are that you much better control over the environment the seed may have. After soaking the seeds as described above, drain the water and put seeds on a piece of window screen or in a small sieve. Put them in a cool place and rinse them twice a day. An alternative for keeping them wet their turn gently in wet paper towels.

Branch seeds just until they germinate to prevent break down more sprouts. If you are not ready to plant, you can put the seeds in the refrigerator to slow down growth.

This pre-emergence process can also be done to test whether old seeds are still viable. Only pre-sprout a few of the questionable seeds to see how they are doing.

Extra Heat

Most seeds will germinate without additional heat, but for a faster, more robust growth, a heat mat is a wonderful invention. This works especially well if you germination station in a cool room, basement or garage.

I have this Hydrofarm heat mat is used with great success. Gently and reliably heated seeds. My seeds heat like this looks fantastic with additional heat. These include tomatoes, eggplant, peppers, squash, cucumbers and melons. I find it particularly carpet well made and durable. It uses only 45 watts of power to warm the root area 10 to 20 degrees over the ambient temperature. For security-conscious, I would like this mat is UL listed and have a waterproof construction. I wish it had a power cord that is longer than his six feet.

When using a heat mat your seed so quickly that you need to keep an eye on them to prevent them germinate leggy. Make sure you set up your grow lights, because they go very quickly possible, within 2-3 days, depending on what you plant.

Optimal germination outdoor environments

Here are two tables with germination preferred temperatures. The first is the soil temperature. Among these are the air temperatures.

Land - not air - temperature is the trigger for germination. Soil temperature change gradually. Factors that influence the process includes exposure soil to sunlight, texture, moisture content and surface (low-lying, flat or mounded).

Gardeners can expect particular soil temperatures to bring specific results. Most germinate cool-loving vegetable garden only when the soil reaches an average 45 degrees. Seed for warm-loving plants wait until the typical temperatures above 55 F.

The only sure way to know when it is safe to plant is to take the temperature of the soil.

Buy a thermometer with metal research offers a flat dial that low readings (in other words, not an oven temperature meat thermometer, although it looks similar). Plan to take the temperature of your garden between 10 and 11:00 - the midpoint between when daily temperatures coolest (dawn) and warmest (late afternoon). Press the thermometer 1.5-2 inches into the ground at various locations.

I use this digital thermometer ground. It is easy to read with its digital display and it takes to stabilize only about 30 seconds and sign my soil temperature. It's really nice to this land information verified quickly and easily.

Do the thermometer in the ground. Store it indoors between lectures.

A strong, prolonged cold front may take soil temperatures again, especially just after they eventually warm up to 45 or 55 F in the spring. Because soil temperatures are likely to rise and fall as slow but a reading of 45 or 55 degrees usually means it is safe to plant.

To planted early is not always fatal for seeds. Many will just sit and wait for the soil to warm. But with warm-loving crops in particular, the seeds can remain viable for very long. If they germinate, their delaying effect on the plant health or output.

Cherry Blossom Seeds Germination

A pretreatment with Stratification (mimic winter germination for certain kinds encourage seed) is recommended for most Cherry Blossom (Sakura) seeds reach high germination rate.

Here are the steps for stratification:

Preparation for Stratification:

1. Zip loc bag
2. Some moist kitchen paper
3. Plant labels
4. 10% Hydrogen peroxide solution(common bleach) *optional but recommended
5. Sieve
6. A pair of gardening gloves 
7. A pair of Tweezers

Steps for Stratification:

1. Rinse the Sakura (Cherry Blossom) seeds gently in a sieve.

2. Use a gardening gloves and soak the Sakura (Cherry Blossom) seeds into the 10% hydrogen peroxide solution for about 10 minutes.* This step is optional but it helps prevent possible molding drastically.

3. Pick up the seeds with a pair of tweezers and put them into a moist kitchen paper, then put them into a zip loc bag. Finish by labeling  them and then refrigerate them. (Do not put into a freezer. Let them stay in the lower part of a refrigerator - the part where you usually store vegetables or fruit will be fine.)

4. Sprouting should start in 2-8 weeks, depending on the variety. Some variety takes up to months to start germination. Check for germination once a week and if necessary ,moisturize the kitchen paper to maintain humidity.   

*If you prefer not to use stratification,starts here:

Here are the steps for direct germination or transferring of seedlings after stratification:

Preparation:

1. Potting mix (detailed in the product listing information and on the seed package).Basically,ask the nursery for a compost for compost designed for Rose should fits well. Preferably,add about 30% of coarse sand (or any sandy soil) to achieve better drainage).The compost should be slightly acidic and a bit sandy. To minimize possible molding problem, make sure the compost you bought is sterile (most commercial compost are). Preferably, buy a new pack instead of using an already opened one.
2. Seed Tray.
3. 10% Hydrogen peroxide solution(common bleach) *optional but recommended
4. Gardening glove
5. A pair of Tweezers
6. Copper based fungicide
7. Sieve

Steps:

1. Rinse the Cherry Blossom seeds gently in a sieve.
2. Use a gardening glove and soak the Sakura (Cherry Blossom) seeds into the 10% hydrogen peroxide solution for about 10 minutes.* This step is optional but it helps prevent possible molding drastically.
3. Pick up the seeds with a pair of Tweezers. Sow your seeds on to the top layers of your growing medium in your pot or in seed trays. Cover the seeds with a thin layer of soil - not more than 2 cm.**If you have already treat the seeds with stratification,starts here:  transfer the seedlings with a pair of tweezers and plant them into the soil.
4. Light can enhance germination. Try putting the seed tray or pot under sunlight as much as possible. 
5. Maintain a medium level of humidity for the germination by regular watering. 
6. Germination of this type of seed should naturally occurs in 2-8 weeks.
7. (Optional but recommended)Once germinate, or after transferring seedlings from stratification,use a Copper based fungicide to prevent molding problems. Follow instruction on the fungicide label for amount and frequency of application.

Notes:

1. Do not plant the seeds or seedlings under extremely temperature. Temperature below 15 degree Celcius or above 30 degree Celcius normally guarantee a poor result. 
2. Stratification is not necessary if the seeds are very fresh (e.g. just harvested in season). Germination rate decreases longer the seeds is stored. Thus, if you are unsure how long your seeds has been stored, treatment of stratification is highly recommended.