The scheduling of effective disease management measures is not a simple task nor can it be standardized. The activities of the organisms that cause plant diseases are not governed by the clock or the calendar. Their activity is influenced by temperature, relative humidity, soil moisture, and other highly changeable environmental factors. Strict scheduling is made even more difficult in the landscape because many different species of plants are being maintained, each with its own, often unique, diseases. As a result, the timing of pesticide application as well as other disease management practices must be tailored to the plant species being grown, the diseases that are present or could pose a serious threat, and the environmental conditions at the site.

Tailoring a very effective disease management plan for a client can be done if notes are taken and records kept on the plants, planting site, weather conditions, and the diseases that occur. With such records, the plan can be adjusted and improved over the years, increasing its effectiveness and, in some cases, reducing the use of pesticides. Use the following information as an outline for the kinds of useful data to keep.

1. Make an inventory of the plants at the site, noting the identity and location of the plants. Mapping and numbering their location on the map will help.
2. Note the important characteristics of the site such as exposure to wind, proximity to road, walks, drainage pattern. Record the date of any site changes such as excavation, paving, removal of overstory trees.
3. Record the general weather conditions at the site during the year including drought, flooding, and wind.
4. a. Record the general appearance and health of each plant being maintained. Especially note unusual characteristics such as smaller than average leaves, unusually light green leaves, smaller than average internode length, and mechanical injuries.
   b. Each year record for each species the approximate date of leaf budbreak, first flowering, and full leaf and twig expansion. Note the date of the first occurrence of the diseases you most want to control.
5. Record the use of insecticides, fungicides, herbicides, fertilizers, or any other chemicals on or near the individual plants or near the general site. Note the chemical, formulation, rate and method of application, and weather conditions at the time of application as well as the time of day the material was applied.

This history of the site and of individual plants will later allow you to accurately identify those plants already diseased, new diseases, general declines in growth, or chemical damage. Knowing what diseases are present and when they occur will greatly improve disease management effectiveness.

The occurrence of key diseases and the timing of important disease management activities can be roughly grouped into four different categories according to the activity of the plant or general weather conditions.

1. Dormant season: late autumn to winter
   • Conduct inventories.
   • Run soil tests to check pH and fertilizer status.
   • Mulch to protect roots.
   • Protect evergreens from drying winds, salt sprays, and ice damage.
   • Prune dead, cankered twigs and branches.
   • Rake and destroy fallen leaves around trees and shrubs that had leaf spotting diseases, especially rose black spot, apple scab, and anthracnose.
   • Examine the plants for galls such as those caused by cedar-apple rust (on juniper), white pine blister rust, pine-pine gall rust, black knot on plum and cherry, and crown gall. Remove infected branches or remove severely affected plants entirely.
   • Late in the dormant season at or near the time of bud swell, spray for black knot of plum and cherry, oak leaf blister, peach leaf curl, and fire blight as just one phase of controlling these diseases.
2. Bud break: spring to early summer
   • Spray to protect emerging leaves of plants that have a history of severe anthracnose, leaf spots, or twig blights, or are at high risk to these diseases.
     
     

     Diseases of primary concern include:
     Sphaeropsis tip blight	Phytophthora dieback
     Juniper twig blight	Volutella on pachysandra
     Apple scab	Douglas-fir needlecasts
     Rose black spot	Cedar-apple rust
     Dogwood anthracnose	Pine-pine gall rust
     Ovulinia petal blight	Fire blight

     
     
   • Pick off and destroy any gall or gall-like tissue such as cedar-apple rust galls from junipers and leaf and flower galls from azaleas.
   • Apply soil drench fungicides to azaleas and rhododendrons which are at risk to Phytophthora root rot.
3. Summer
   • Apply fungicides, during wet weather per class="text"iods, to prevent the further spread of diseases including:
     • Apple scab
     • Rose black spot
     • Volutella on pachysandra
   • Apply soil drench fungicides to continue the Phytophthora protection. Do this at the recommended interval noted on the product label.
   • Apply fungicides to control pine and spruce needlecasts.
4. Cool weather: late summer to autumn
   • Spray to control powdery mildew on highly susceptible plants such as roses, particularly during cool night-warm day periods.
   • Spray to protect the new autumn growth on plants such as junipers from twig blight infection.
   • Prepare new planting sites that should be fumigated and treat them while soil temperatures remain above 55 degrees F and soil moisture is 50 to 85% of field capacity. Allow the site to aerate several weeks before planting or cover the treated area with a plastic tarp and plant in the spring.
   • **Update the site inventory and be certain you have recorded all the diseases that developed on each plant.

In addition to these four key periods of disease control, times during which plants are under stress (such as drought or defoliation) should be shortened as much as possible, through watering, insect control, etc. Stresses weaken plant vigor rendering them more susceptible to weak plant parasites that can cause cankers and root rots.

The following table lists some woody ornamentals, diseases found on them and management strategy. Key plants and diseases are listed in this color.

	Dormant	Bud break	Summer	Autumn
Arborvitae (Thuja)
Kabatina twig blight	P	BSp		BSp
Phomopsis twig blight	P	BSp		BSp
Root rot			D
Ash (Fraxinus)
Anthracnose				R
Azalea (Rhododendron)
Botrytis blight		BSp
Leaf gall		P-BSp*
Leaf spots		BSp		R
Nematodes				F
Ovulinia flower blight		BSp
Phytophthora dieback	P	BSp	CSp	CSp-P
Powdery mildew			BSp	CSp
Root rots		D	D	F
Boxwood (Buxus)
Canker	P	BSp		BSp
Macrophoma leaf spot	P		I
Nematodes				F
Root rot				F
Catalpa (Catalpa)
Leaf spots				R
Powdery mildew				NT
Verticillium wilt				NT
Cherry (Prunus)
Bacterial leaf spot		BSp	CSp
Black knot	P-X*	BSp
Coccomyces leaf spot			BSp
Chestnut (Castanea)
Blight	P-X*
Leaf spot				R
Cotoneaster (Cotoneaster)
Fire blight	P-BSp*	CSp	CSp
Scab		BSp	CSp
Crabapple (Malus)
Cedar-apple rust			NT
Fire blight	P-BSp*	CSp*	CSp*
Powdery mildew			NT
Scab		BSp	CSp	R
Dogwood (Cornus)
Anthracnose	P	BSp	CSp
Decline	P-X*	BSp	CSp-I	I
Septoria leaf spot		BSp	CSp
Powdery mildew		BSp	CSp
Douglas fir (Pseudotsuga)
Rhabdocline needlecast		BSp
Swiss needlecast		BSp
Elm (Ulmus)
Botryodiplodia canker	P		I	I
Dutch elm disease			X	X
Black leaf spot			NT	R
Phloem necrosis			X
Wetwood			NT
Euonymus (Euonymus)
Anthracnose		BSp	CSp	R
Crown gall	P-X*
Root rot			D
Forsythia (Forsythia)
Crown gall	P-X*
Hackberry (Celtis)
Witches' broom	P
Hawthorn (Crataegus)
Fire blight	P	BSp	CSp
Leaf spot		BSp*	CSp*
Rust		BSp*
Holly (Ilex)
Nematodes				F
Thielaviopsis root rot			D
Honeysuckle (Lonicera)
Powdery mildew				BSp
Ivy, Boston (Parthenocissus)
Black rot		BSp	CSp	CSp
Ivy, English (Hedera)
Colletotrichum leaf spot	P	BSp	CSp
Bacterial leaf spot	P	BSp	CSp
Juniper (Juniperus)
Cedar-apple rust	P-X*
Kabatina twig blight	P	BSp		BSp
Phomopsis twig blight	P	BSp		BSp
Root rot	X*		D
Leucothoe (Leucothoe)
Leaf spot		BSp	CSp
Root rot		D
Lilac (Syringa)
Bacterial leaf blight	P	BSp*
Powdery mildew			BSp	CSp
Maple (Acer)
Anthracnose				P-R
Bleeding canker				X*
Leaf spots				NT
Verticillium wilt				X*
Mountain Ash (Sorbus)
Cytospora canker	P		I
Fire blight	P
Leaf spot		BSp*		R
Mountain Laurel (Kalmia)
Leaf spot		BSp*	CSp*	R
Oak (Quercus)
Anthracnose				R
Bacterial leaf scorch				X*
Decline			I
Leaf blister	BSp*
Pachysandra (Pachysandra)
Volutella blight	X	BSp	CSp	X
Pear (Pyrus)
Fire blight	P-BSp*	CSp	CSp
Scab		BSp	CSp
Pieris (Pieris)
Phytophthora dieback	P	BSp	CSp	CSp-R
Root rot			D	F
Pine (Pinus)
Sphaeropsis tip blight	P	BSp-P
Needle blights		BSp
Cyclaneusma Needlecast		BSp	CSp	CSp
Lophodermium Needlecast			BSp
Hypoderma Needlecast		BSp	CSp
Root rots			D	F
Gall and cankering rusts	P-X*	BSp
Pyracantha (Pyracantha)
Fire blight	P	BSp-P	P
Scab		BSp	CSp
Rhododendron (Rhododendron)
Botryosphaeria dieback	P		I	I
Cercospora leaf spot		BSp*	CSp*	R
Ovulinia flower blight		BSp		R
Phytophthora dieback	P	BSp	CSp	CSp
Root rot			D	F
Rose (Rosa)
Black spot	P	BSp	CSp	CSp-R-P
Cankers	P-X*
Powdery mildew			BSp	CSp
Rust	PR	BSp	CSp	R
Spruce (Picea)
Cytospora canker	P		I	I
Needlecast		BSp
Sycamore (Platanus)
Anthracnose	P			R
Powdery mildew				NT
Viburnum (Viburnum)
Leaf spot				R
Vinca (Vinca)
Blight	X*	BSp	CSp	X*
Walnut and Butternut (Juglans)
Anthracnose	P			R
Bacterial blight		BSp
Willow (Salix)
Crown gall	P-X*
Leaf blight	P			R

ABBREVIATIONS of suggested control techniques to employ at each key management time:

*	Only if the disease had been severe
BSp	Begin spray schedule-discontinue when weather dries
CSp	Continue spraying if wet-discontinue when weather dries
D	Apply soil drench fungicides
F	Fumigate before planting
I	Irrigate to prevent drought stress
NT	No treatment required
P	Prune
R	Rake and destroy fallen leaves
X	Remove infected plant