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Southern Pine Nursery Disease Development Calendar

Prepared by Steven W. Oak, plant pathologist USDA Forest Service, S&PF. Thanks to E.L. Barnard, C.E. Cordell, R.L. Anderson and G.M Blakeslee for photos and review.

This chart is intended to illustrate the major diseases affecting southern pine bareroot nursery stock and when they occur. The width of the bar indicates the changing potential severity of each disease as the season progresses from seed sowing to seedling outplanting. Where information on disease progress in unavailable for the storage-transport period between lifting and outplanting and the post-outplanting period, dotted lines rather than solid bars appear. Not all diseases are pictured and some diseases may be more serious in localities than pictured. The causal agents, commonly expressed symptoms and pertinent comments for each disease are detailed in a table below. Two or more conditions may affect a seedling crop simultaneously, complicating symptom expression and diagnosis. Forest nursery pest specialists should be consulted when abnormalities occur.

DISEASE CAUSE SPECIES AFFECTED SYMPTOMS
1 Fusarium spp. (F. solani, F. oxysporum, others) All pines a, b, c, d, e
2 Many Pythium spp. All pines a, b, c (occasionally), d, e (succulent root tissue)
3 Several Phytophthora spp. All esp. Sand Pine a, b, c, d, e, I (on lignified root tissue)
4 Rhizoctonia solani All pines a, b, c, d, e
5 Rhizoctonia solani Longleaf Pine a, b, c, h
6 Sclerotium bataticola and Fusarium spp. All pines a, b, c, d, e
7 Cronartium quiercuum f. sp. Fusiforme Slash and Loblolly Pine f
8 Fusarium moniliforme var. Subglutinans Loblolly Pine and esp. Slash Pine c, I (internal + external), k (lesion develops on tissue of all ages)
9 Scirrhia acicola Longleaf Pine g, h, j
10 Meloidogyne, Meloidodera, Pratylenchus, other spp. All pines a, b, c (occasionally), d, l (occasionally)
11 High soil temperatures All pines c, k (succulent tissue)
12 Imprecise application: Disregard for label specifications All pines a, b, c, d (possibly), g, h
13 Soil pH excess: Lack of soil amendments All pines a, b, d, g
14 Extended storage at higher than optimal temperatures (molds, yeasts) All pines c, h, m

 

Comments:
1, 5, 8 can be seed-borne
1, 2, 3, 4, 5, 6, 8 can cause damping off; accentuated by cool soil temps, delayed germination.
2, 3 worst in wet conditions.
1, 2, 3, 4, 5, 6, 8 can be controlled by adequate soil fumigation with methyl bromide-chloropicrin fumigants.
5 affects radicle and roots early; foliage thereafter; spread rapid after canopy closes.
8 affects seedlings singly or in small groups; all others usually affect larger groups.
9 may result in extended grass stage when outplanted.
10 worst in second and subsequent seedling crops after fumigation.
Outplant failures can result from 6, 7, 8.

Symptom Key:
a - stunting
b - yellowing
c - mortality
d - root system sparse
e - roots decayed
f - basal stem swelling
g - foliage mottling (yellow or necrotic)
h - foliage browning
I - pitching
j - chlorosis in bands on needles
k - necrotic lesion at or near ground line
l - knots on roots
m - fungal growth on foliage and roots

 

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