Beef Steak Plant Brown Stem Base

Tomato  Disease  Identification  Key By Affected Plant Part: Stem and Whole Plant Symptoms Generalized tomato plant adapted from Plant Pathology 4th edition by G. N. Agrios copyright 1997 as Figure 1-1 published by Academic Press, San Diego, CA, with permission from Elsevier.

Stem and Whole Plant Symptoms (Crown rot, damping off, roots, stunting, wilt, and vascular discoloration ) by Pathogen Groups and Other Causes.
	Oomycetes Damping off Buckeye rot Late blight	Phytoplasma Big bud Nematodes Northern root-knot Southern root-knot Parasitic plants Dodder(Cuscuta spp.) Damage From Herbicides 2,4-D (Phenoxy) Banvel Treflan Roundup Damage From Insecticides Malathion Thiodan	Damage From Insects Broad mite Hornworm Physiological/Weather Physiological leafroll Walnut wilt Hail damage Lightning damage Nutritional Disorders Nitrogen Phosphorous Magnesium Manganese Iron

Tomato  Disease  Identification  Key

Bacterial		Plant Part Affected				Other parts affected
		Stem	Whole Plant	Roots	Characteristic Symptoms
	Canker	X	X	X	browning of vascular tissue and browning and mealy appearance of pith at crown and above; external discoloration, enlargement of nodes and stem cracking sometimes occurs; yellow and necrosis of plant associated with plant wilt; foliage characteristically remains attached to plant	leaves, fruit
	Speck	X	X		tiny, dark brown to black spots with surrounding yellow halo; may result in leaf and plant stunting	leaves, fruit
	Spot	X	X		dark brown, oval to elongated spots; coalesce to streaks; considerable loss of lower leaf foliage can occur	leaves, fruit
	Pith necrosis	X	X	X	yellowing and wilting of leaves, blacking and enlarging of petioles and nodes, and progressing to top of plant; yellowing and wilt of entire plant	leaves
	Stem rot	X	X		outward blacking of stem and leaf tissue; blackened pith tissue	leaves
	Crown gall	X	X	X	plant stunting and wilting; gall formations obvious on roots	leaves
	Bacterial wilt	X	X	X	yellowing followed by leaf necrosis and wilting of entire plant; longitudinal cutting of stem reveals brown vascular discoloration and eventual hollowness	leaves

Fungal
		Stem	Whole Plant	Roots	Characteristic Symptoms	Other parts affected
	Alternaria stem canker	X	X		dark brown stem cankers with concentric rings; cankers may girdle plant	leaves
	Early blight	X	X		on stems appears as lesion with dark border and gray center; can encompass and girdle stem causing death of lower canopy leaves	leaves, fruit
	Damping off (Rhizoctonia)	X	X		responsible for damping off in the small seedling stage; causes restrictions near the plant crown resulting in wilting and death	leaves
	Fusarium crown and root rot	X	X	X	brown vascular tissue in stem from crown to slightly above; stem surface can be brown; roots are brown and rotting
	Fusarium wilt	X	X	X	brown vascular tissue in stem from crown to far above
	Gray leaf spot		X		symptoms are restricted to leaves and whole plant affects	leaves
	Gray mold	X	X		large, light brown elliptical spots; gray fungal growth; lesions can girdle the stem resulting in plant death	leaves, fruit
	Leaf mold	X	X		can result in considerable leaf defoliation but unlikely resulting in plant death
	Powdery mildew (Leveillula)	X	X		affected plants can show considerable defoliation, but not resulting in plant death	leaves
	Powdery mildew (Oidium)	X	X		affected plants show considerable defoliation, but not resulting in plant death	leaves, flower parts
	Septoria leaf spot	X	X		dark elongated spots develop on petioles and stems leading to loss of lower canopy, and unthrifty plants; concern with overwintering inoculum for the next season	leaves, flower parts
	Southern blight	X	X		fungus can cause damping off or in older plants a crown rot leading to wilt and plant death; look for tan sclerotia in mass of whitish fungal growth above the soil line
	White mold	X	X		brown soft rot of stem at crown or above; becomes light gray; white cottony fungal growth when moist; hard, black, pea-like objects (sclerotia) eventually form; causing wilt and eventual plant death
	White mold minor	X	X		similar to above but with smaller sclerotia
	Target spot	X	X		stem lesions may eventually girdle the stem and result in plant death	fruit, leaves
	Verticillium wilt	X	X	X	brown vascular tissue in stem at crown of plant; plants will wilt in the heat of the day	leaves

Oomycetes					Characteristic Symptoms	Other parts affected
		Stem	Whole Plant	Roots
	Damping off (Pythium)	X	X	X	common cause of seedling loss with water-soaked and mushy stems; results in stem girdling and plant wilt and death
	Buckeye rot	X	X		can cause seedling damping off; on older plants can cause vascular discoloration affecting roots and stem	fruit
	Late Blight (several genotypes)	X	X		newer genotypes of late blight are more aggressive, especially to stems; plant death is common under wet and cool and moderately warm temperatures; see leaf and fruit section for more images	fruit, leaves

Viruses					Characteristic Symptoms	Other parts affected
		Stem	Whole Plant	Roots
	Alfalfa mosaic	X	X	X	yellowing and bronzing with necrosis of leaves; leaves stop growing and curl downward; longitudinal cut of stem reveals brown streaking of phloem and pith; also noted in roots; frequently occurs when tomatoes are planted next to alfalfa (illustrated) or red clover infected fields	fruit, leaves
	Cucumber mosaic	X	X		plant stunting and malformation of foliage is common especially if plants are infected at an early age	fruit, leaves
	Curly top	X	X		plants have an erect growth habit, are stunted and leaves are curled upward	fruit, leaves
	Potato leafroll	X	X		plants are stunted and have yellowing leafroll symptoms especially if infected at an early age	fruit, leaves
	Potato virus Y	X	X		plants are stunted and have downward curling leaves with mottle, veinbanding and possible necrosis depending on the strain involved	fruit, leaves
	Pseudo curly top	X	X		plants are stunted with greatly reduce foliage with upward curling leaves; found in south Florida and spread by treehoppers	fruit, leaves
	Tobacco etch	X	X		plants are stunted and foliage shows extensive rugosity when plants are infected at an early age	fruit, leaves
	Tobacco (tomato) mosaic	X	X		depending on the strain and age of plants when infected, plants are stunted with mosaic or fernleaf like symptoms	fruit, leaves
	Tobacco mosaic & potato virus X	X	X		plants are stunted and show a great amount of black streaks on leaves, stems and discoloration on fruit	fruit, leaves
	Tomato yellow leaf curl	X	X		a devastating viral diseases of cultivated tomato in tropical and subtropical regions worldwide, and now present in southern US; denoted by plant stunting and pronounced chlorotic leaves that curl upward	leaves
	Tomato spotted wilt	X	X		Plants show a variety of symptoms depending on when plants are infected; young plants show necrotic streaks or spots along with leaf distortion; older plants show yellowing and bronzing on the foliage, stunt and wilting from the apical tissue to the lower plant parts	fruit, leaves

Viroids
		Stem	Whole Plant	Roots	Characteristic Symptoms	Other parts affected
	Tomato bunchy top	X	X		stunting, apical proliferation, leaf narrowing, chlorosis, necrosis, crinkling and brittleness of leaf tissue
	Tomato apical stunt	X	X		see above
	Tomato planta macho	X	X		see above

Phytoplasma					Characteristic Symptoms	Other parts affected
		Stem	Whole Plant	Roots
	Big bud	X	X	X	stiff erect growth, brittleness, leaf yellowing or purpling; aerial roots	fruit, leaves

Nematodes				Characteristic Symptoms	Other parts affected
	Stem	Whole Plant	Roots
Northern root-knot		X	X
Southern root-knot		X	X

Parasitic Plants					Characteristic Symptoms	Other parts affected
		Stem	Whole Plant	Roots
	Dodder (Cuscuta spp.)	X	X

Damage From : Herbicides					Characteristic Symptoms	Other parts affected
		Stem	Whole Plant	Roots
	2,4-D	X	X		fernleaf-like symptoms of foliage with leaf curl and plant stunting	fruit, leaves
	Banvel	X	X	X	plant stem deforming with aerial foot initials	leaves
	Treflan	X	X	X	stem and crown damage with swelling and loss of roots; whole plant stunting	leaves
	Roundup	X	X		plant stunting and leaf rolling with leaf center chlorosis; degree of damage depends on dosage and plant stage at exposure	fruit, leaves

Damage From : Insecticides					Characteristic Symptoms	Other parts affected
		Stem	Whole Plant	Roots
	Malathion	X	X		plant unthriftiness and marginal chlorosis and necrosis; seen with older formulations	leaves
	Thiodan	X	X		leaf and petiole burn but general no plant stunting; localized	leaves

Damage From: Insects					Characteristic Symptoms	Other parts affected
		Stem	Whole Plant	Roots
	Broad mite				plants are stunted and leaves are irregularly shaped and twisted enough so as to show an overall pattern of affected plants in the field
	Hornworm	X	X		extensive removal of leaves, stems and petioles	fruit, leaves

Damage From: Physiological/Weather
		Stem	Whole Plant	Roots	Characteristic Symptoms	Other parts affected
	Physiological leafroll	X	X		leafrolling seen on entire plant leading to an unthrifty appearing plant	leaves
	Walnut wilt	X	X		poor plant growth and plant wilt when plants are grown in the root zone of walnut and butternut trees	leaves
	Hail damage	X	X		spotty plant damage consisting of necrotic depressions and wholes to leaves, petioles and stems	fruit, leaves
	Lightning damage	X	X		damage occurs in circular pattern with most severely affected plants in center; branches, stems and petioles show shrinkage due to collapse of pith; ladder-like internal stem damage	leaves

Damage From: Nutritional Disorders					Characteristic Symptoms	Other parts affected
		Stem	Whole Plant	Roots
	Nitrogen	X	X		plant stunting may occur and oldest leaves turn chlorotic and younger leaves turn yellowish-green	leaves
	Phosphorous	X	X		leaves on young seedlings turn purplish and the leaves on older plants are unthrifty and turn reddish-purple on the undersides	leaves
	Magnesium	X	X		interveinal chlorosis begin on oldest leaves and continue to younger leaves; midribs remain green and leaves may become necrotic	leaves
	Manganese	X			a checkerboard appearance of interveinal yellowing beginning on apical leaves and near the main veins	leaves
	Iron	X	X		interveinal yellowing or whitening beginning on apical leaves with veins remaining green	leaves

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Source: http://vegetablemdonline.ppath.cornell.edu/DiagnosticKeys/TomWlt/TomWiltKey.html

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