diseases covered rhizoctonia crown rot and blight rhizoctonia crown rot and blight botrytis blight...

Download Diseases Covered Rhizoctonia Crown Rot and Blight Rhizoctonia Crown Rot and Blight Botrytis Blight Botrytis Blight Black Spot Black Spot Daylily Rust Daylily

Post on 27-Mar-2015

215 views

Category:

Documents

2 download

Embed Size (px)

TRANSCRIPT

  • Slide 1

Diseases Covered Rhizoctonia Crown Rot and Blight Rhizoctonia Crown Rot and Blight Botrytis Blight Botrytis Blight Black Spot Black Spot Daylily Rust Daylily Rust Slide 2 Rhizoctonia crown and root rot. Caused by Rhizoctonia solani Caused by Rhizoctonia solani Root rot may develop either in the rooting cube or on rooted cuttings transplanted to pots as the crop is finished for retail. Infected roots become water-soaked then brown. Root rot may develop either in the rooting cube or on rooted cuttings transplanted to pots as the crop is finished for retail. Infected roots become water-soaked then brown. Both root tips and sections of the root away from the tip may develop symptoms. Crown rot can develop on the stem as lesions expand from stem infections occurring during propagation. Both root tips and sections of the root away from the tip may develop symptoms. Crown rot can develop on the stem as lesions expand from stem infections occurring during propagation. Slide 3 Stem lesions may develop at a much slower pace on rooted plants, since this tissue is more hardened off and thus more resistant than stems of newly made cuttings. Stem lesions may develop at a much slower pace on rooted plants, since this tissue is more hardened off and thus more resistant than stems of newly made cuttings. Foliar symptoms of crown and root rot include chlorosis, leaf necrosis, wilting, defoliation, and plant death, but often the most common symptom is stunting. Foliar symptoms of crown and root rot include chlorosis, leaf necrosis, wilting, defoliation, and plant death, but often the most common symptom is stunting. Root rot infections may be initiated from lesions on stems or from inoculum introduced to the potting mix from debris surviving in the greenhouse. Root rot infections may be initiated from lesions on stems or from inoculum introduced to the potting mix from debris surviving in the greenhouse. Generally, moist but not wet conditions in the potting mix favor development of Rhizoctonia crown and root rot on potted plants. Generally, moist but not wet conditions in the potting mix favor development of Rhizoctonia crown and root rot on potted plants. Spacing plants with a full canopy too close together can result in moisture and soil temperatures favorable for development of disease due to shading of the container surface. Spacing plants with a full canopy too close together can result in moisture and soil temperatures favorable for development of disease due to shading of the container surface. Rhizoctonia crown and root rot. Slide 4 Rhizoctonia Damping off Slide 5 Rhizoctonia Crown Rot Poinsettia Slide 6 Rhizoctonia Blight Begonia Slide 7 Rhizoctonia blight Impatiens Slide 8 Control Control of stem and root rot begins with thorough removal of all crop debris from the production facility at the end of a cropping cycle. Control of stem and root rot begins with thorough removal of all crop debris from the production facility at the end of a cropping cycle. Sanitation of work area and bench surfaces with surface disinfectants is important. Sanitation of work area and bench surfaces with surface disinfectants is important. During propagation, misting cycles should be monitored closely to avoid over wetting foliage of cuttings once newly made cuttings become turgid. During propagation, misting cycles should be monitored closely to avoid over wetting foliage of cuttings once newly made cuttings become turgid. In greenhouse production facilities with a history of Rhizoctonia stem and root rot, soaking dry rooting strips in a fungicide solution can protect cuttings from disease In greenhouse production facilities with a history of Rhizoctonia stem and root rot, soaking dry rooting strips in a fungicide solution can protect cuttings from disease Generally one application of fungicide is sufficient to protect the crop during the propagation cycle. Generally one application of fungicide is sufficient to protect the crop during the propagation cycle. After transplanting, fungicide drenches may be needed at regular intervals to prevent crown and root rot After transplanting, fungicide drenches may be needed at regular intervals to prevent crown and root rot Slide 9 Botrytis Blight CAUSAL ORGANISM: Botrytis cinerea Botrytis blight is common in all parts of the world. This fungus is not a specific pathogen and can take advantage of many situations to produce a blight or rot condition on many hosts. It is an opportunist on cut or pruned rose canes and will infect flowers and buds. Slide 10 Slide 11 Symptoms/Signs The most common symptoms usually are seen on young flower buds which droop, turn black at the base and later produce the cottony grey- black mycelium of the fungus. Flowers can also be affected in the same way and cut ends will have the black canker like symptoms with presence of mycelium. Cool and wet conditions facilitate grey-black mycelial growth of Botrytis. Slide 12 Botrytis Stem Canker Impatiens, Poinsettia Slide 13 Botrytis Blight Slide 14 Botrytis Crown Rot - lisianthus Slide 15 Botrytis Blight Geranium Results from infected flowers Slide 16 Botrytis Dieback - Geranium Slide 17 Botrytis Blight Slide 18 Disease Cycle This fungus is not specific and will grow on many different plants and plant debris. This fungus is not specific and will grow on many different plants and plant debris. Under cool wet conditions profuse sporulation results and spores are moved to roses by air currents or blowing rain. Under cool wet conditions profuse sporulation results and spores are moved to roses by air currents or blowing rain. A minor wound in a bud or flower, or perhaps a pruning cut will provide the initial point of entry. A minor wound in a bud or flower, or perhaps a pruning cut will provide the initial point of entry. As the infection progresses more sporulation results and additional sites become infected. As the infection progresses more sporulation results and additional sites become infected. The fungus is a low level parasite and will colonize wound sites as well as dead plant material. The fungus is a low level parasite and will colonize wound sites as well as dead plant material. Slide 19 Control Prevention is the best means of control. This can be accomplished through intense sanitation procedures. Prevention is the best means of control. This can be accomplished through intense sanitation procedures. By elimination of opportunistic colonization on dead plant material the amount of sporulation can be reduced. By elimination of opportunistic colonization on dead plant material the amount of sporulation can be reduced. Good ventilation is also essential in reducing disease incidence. Some sprays may give short term relief but the fungus usually becomes quickly resistant. Good ventilation is also essential in reducing disease incidence. Some sprays may give short term relief but the fungus usually becomes quickly resistant. In greenhouse conditions special covers are used to reduce the levels of ultraviolet light required by the fungus for sporulation. In greenhouse conditions special covers are used to reduce the levels of ultraviolet light required by the fungus for sporulation. In most cases, removal of infected plant parts and protection of wounds by chemicals is all that can be done until warmer and dryer conditions prove too unfavorable for continuing disease. In most cases, removal of infected plant parts and protection of wounds by chemicals is all that can be done until warmer and dryer conditions prove too unfavorable for continuing disease. Slide 20 Black Spot Caused by the fungus Diplocarpon rosae. The disease can cause almost complete defoliation of bushes by early fall. Caused by the fungus Diplocarpon rosae. The disease can cause almost complete defoliation of bushes by early fall. It produces a weakened bush on which cane dieback, stem canker, and winter injury can become severe. It produces a weakened bush on which cane dieback, stem canker, and winter injury can become severe. Slide 21 Slide 22 Symptoms Circular black spots ranging from 1/16 inch to 1/2 inch in diameter appear generally on leaves upper sides. Circular black spots ranging from 1/16 inch to 1/2 inch in diameter appear generally on leaves upper sides. The spots are frequently surrounded by a yellow halo. Infected leaves characteristically turn yellow and fall prematurely. The spots are frequently surrounded by a yellow halo. Infected leaves characteristically turn yellow and fall prematurely. This leaf spot can be distinguished from others by the fringed margin and consistently black color. This leaf spot can be distinguished from others by the fringed margin and consistently black color. Cane infection produces a reddish-purple spot. Cane infection produces a reddish-purple spot. In many varieties, pale flower color is indirectly caused by infection. In many varieties, pale flower color is indirectly caused by infection. Slide 23 Disease Cycle Black spot is spread by splashing water. Infection occurs after leaves are wet for several hours. Black spot is spread by splashing water. Infection occurs after leaves are wet for several hours. Therefore, the disease is more serious during periods of rainfall. Therefore, the disease is more serious during periods of rainfall. Slide 24 Control A preventive program for black spot should begin with a thorough cleanup in the fall. Diseased leaves on the ground should be raked and destroyed. A preventive program for black spot should begin with a thorough cleanup in the fall. Diseased leaves on the ground should be raked and destroyed. All diseased canes should be pruned off by cutting several inches into good wood. All diseased canes should be pruned off by cutting several inches into good wood. A fungicide program should start in the summer just before leaves become spotted. From then until frost, the leaves may require a protective fungicide

Recommended

View more >