Lecture 16Lecture 16Turf, Flower and Vegetable Turf, Flower and Vegetable

DiseasesDiseases

Turf diseasesTurf diseases

Fusarium patch, red thread disease,

fairy rings and thatch are common in

Seattle

Flower diseasesFlower diseases

• Azalea – leaf and flower gall• Camellia – cold damage• Cherry – brown rot, Botrytis• Geranium – Botrytis blight• Lilac – Botrytis flower blight• Narcissus – chocolate spots?• Pansy – Botrytis blight

Petunia – Botrytis blight• Rhododendron – flower bud damage (frost)• Rose – everything• Tulip –fire – Botrytis, virus

Botrytis (Grey mold)Botrytis (Grey mold)

Rose

Cherry

Roses have earned the reputation of one of the most susceptible plants to diseases and pests; chemical fungicides and pesticides are widely used both by growers and home gardeners……

Some growers now raise roses organically without chemicals, e.g., https://www.ashdownroses.com

A listing of known diseases A listing of known diseases that affect rosesthat affect roses

Described Rose DiseasesDescribed Rose Diseases

*Rose Anthracnose *Rose Anthracnose

*Rose Bacterial Blight*Rose Bacterial Blight

*Rose Black Spot*Rose Black Spot

*Rose Botrytis Blight*Rose Botrytis Blight

*Rose Cankers*Rose Cankers

*Rose Crown Gall*Rose Crown Gall

*Rose Downy Mildew*Rose Downy Mildew

*Rose Hairy Root*Rose Hairy Root

*Rose Leaf Spots*Rose Leaf Spots

*Rose Powdery Mildew*Rose Powdery Mildew

*Rose Rust*Rose Rust

*Rose Spring Dwarf*Rose Spring Dwarf

*Rose Mosaic Virus*Rose Mosaic Virus

Believe it or not, there’s more!!

Rose Diseases and Common Rose Diseases and Common Methods for ControlMethods for Control

Powdery Mildew

(Sphaerotheca pannosa)

• Overwinters in infected buds, canes and fallen leaves and attacks young spring growth.

• Thrives in areas with high relative humidity at night when temperatures are around 60 degrees F.

• Also thrives at around 80 degrees F with 40%-70% RH.

Best way to prevent powdery mildew and other diseases without using chemicals!

• Clean up fallen leaves, deadheads and other debris. DO NOT COMPOST!

• Allow adequate space for plants when planting to ensure good air circulation.

• Avoid overwatering, overhead watering, and applying too much fertilizer.

• Plant “resistant” varieties

Blackspot Blackspot (Diplocarpon rosae)(Diplocarpon rosae)

• Infects foliage and stems causing defoliation and weakens plant.

• Presence of water on plant surface for 7-8 hours is needed for infection.

Other DiseasesOther Diseases

Rose RustPhragmidium ssp.

Botrytis BlightBotrytis cinerea

Crown GallAngrobacterium tumefaciens

Common Diseases of Common Diseases of the Home Vegetable the Home Vegetable

GardenGarden

Carrot - Root Knot NematodeCarrot - Root Knot NematodeMeliodogyne sppMeliodogyne spp..

• Microscopic, live in soil

• Feed on roots• Distortion of roots• Stunted roots, short

bushy root hairs• Yellow or stunted

leaves

CrucifersCrucifersBlack RotBlack Rot

Xanthomonas campestrisXanthomonas campestris

• Bacteria• Enters through wounds

on leaves• Leaves yellow and die in

“V” shaped pattern from margin to midrib

• Leaf Drop• Spreads through xylem to

other parts of plant

Blossom End RotBlossom End Rot

Symptoms:•First appears as a brown discoloration at blossom end of fruit.

•Spot enlarges and darkens, eventually becoming sunken and leathery.

•Soft Rotting may occur if secondary fungi or bacteria invade the spot.

LettuceLettuceBacterial Soft Rot SymptomsBacterial Soft Rot Symptoms

•Rotting of the edges of lower leaves

•Leaves of the head finally dissolve into an unappetizing, slimy rot.

                                            

White mold White mold SclerotiniaSclerotinia rot rot

A fungal disease which may attack the stems, leaves, and pods of beans.

Signs: Purple to brown scabby areas or warty lesions on the surface of the tuber. Small galls and warts may form on roots of some potatoes.

PotatoesPowdery Scab is caused by a fungus, Spongospora subterranea, that is carried on the seed and can survive 3 to 10 years in the soil.

Corn SmutCorn Smut

A fungus (basidiomycete),

Ustilago zeae, overwinters

in soil as teliospores, that

may survive 2 or 3 years.

Spores may be wind blown

long distances.