Fusiform Rust Research Articles

Management Strategies to Reduce Losses from Fusiform Rust

Abstract Fusiform rust of southern pines is a major problem in much of the South. Over the past 50 years the disease has evolved from an occasional problem into a major limiting factor in growing slash and loblolly pines. Intensive site preparation, planting of fast-growing nonresistant seedlings, weed and fire control, and fertilizer application stimulate wood production in pine plantations, but they also favor the spread and increase of fusiform rust. Forest managers struggle to find the optimum balance between maximum productivity and increased susceptibility to fusiform rust. Silvicultural practices being used to reduce losses from fusiform rust include predicting rust hazard for management units, selecting the appropriate method and intensity of site preparation, using resistant planting material, and applying cultural treatments in established stands. South. J. Appl. For. 17(3):146-149.

Comparison of Planted Loblolly and Slash Pine Performance in Southeast Texas

Abstract The performance of young (less than 10 yr) loblolly (Pinus taeda L.) and slash (Pinus elliottii Engelm.) pine trees was compared on planted sites in southeast Texas. Performance was compared for: total tree height; tree diameter; height to live tree crown; tree volume index,; incidenceof fusiform rust (Cronartium quercuum [Berk.] Miyabe ex Shirai f. sp. fusiforme); crookedness of stems; and survival rates. For these young trees, slash pine tended to perform better in southeast Texas than loblolly pine in total tree height, tree diameter, stem size, height to first livebranch and stem straightness. However, loblolly pine was less susceptible to fusiform rust than slash pine, and its mortality rate was lower than slash pine. However, based on the performance of these young plantations, a recommendation on the preferred pine species to plant in southeast Texasmight be premature. South. J. Appl. For. 17(1):26-31.

Twenty-Six New Pine Hosts of Fusiform Rust

Forty-five pine species and cultivars (Pinus spp.) were tested for susceptibility to fusiform rust (Cronartium quercuum f. sp. fusiforme) by inoculation with basidiospores. Twenty-six species or cultivars were found to be susceptible. Eighteen other species were confirmed as susceptible

Detection of DNA Polymorphisms in a Single Urediniospore-Derived Culture ofCronartium quercuumf. sp.fusiforme

PCR (polymerase chain reaction) with single, arbitrarily chosen primers was used to detect DNA polymorphisms among 34 sibling gametothalli (single-basidiospore hyphal cultures) and spermatia (single drops of pycniospores) derived from a single-urediniospore culture of the fusiform rust fungus, Cronartium quercuum f. sp. fusiforme. Ten single-basidiospore hyphal cultures were distinguished by comparing nine polymorphic segments produced by four primers. Polymorphisms also were detected between 24 single drops of pycniospores collected from four different galls and drops within the same gall, revealing that phenotypes of galls were all different, and some contained more than one phenotype []

Growth and Wood Properties in a Carolina Sandhills Pine Seed Source Study

Abstract Eight pine sources were planted on a sandhills site in South Carolina. Total height, dbh, wood specific gravity, tracheid length, and fusiform rust (Cronartium quercum [Berk.] Miyabe ex. Shirai f. sp. fusiforme) infection were evaluated following 17 growing seasons. The Choctawhatcheesource of sand pine (Pinus clausa [Chapm.] Vasey) is apparently well adapted to the deep sands of the Carolina sandhills and exhibited superior height and diameter growth to slash pine, two local sources of loblolly pine (P. taeda L.), and two sources of Virginia pine (P. virginiana Mill.). A combination of excellent growth and reasonable survival resulted in significantly more cubic foot volume per acre than the other seed sources or species included in this study. Despite having the lowest weighted specific gravity of all sources in this planting, the Choctawhatchee sand pineproduced more than twice as much dry weight per acre than any other source. A single open-pollinated family of drought-hardy loblolly pine from Bastrop County, TX, displayed excellent growth, survival, rust resistance, and wood quality. Its performance warrants a more careful and wider evaluationof this seed source for use on these difficult sandhills sites in the Carolinas. South. J. Appl. For. 16(4):164-169

Loblolly Pine Seed Sources Differ in Susceptibility to the Southern Pine Beetle in South Carolina

Abstract In a planting near Aiken, SC, loblolly pine saplings from an eastern seed source were significantly more susceptible to the southern pine beetle (SPB) than were loblolly saplings from western seed sources. Two eastern sources of slash pine also resisted beetle attack. Study plots wereoriginally established to evaluate disease resistance and growth of fusiform rust resistant and susceptible seed lots. There was no relationship between stand characteristics or rust infection patterns and SPB damage. South. J. Appl. For. 16(4):169-174

Indirect Prediction of Breeding Values for Fusiform Rust Resistance of Slash Pine Parents Using Greenhouse Tests

Abstract Six-week-old greenhouse-grown seedlings of 100 open-pollinated slash pine families were artificially inoculated with fusiform rust fungus at the USDA Forest Service Resistance Screening Center (RSC). All families had been tested for rust resistance in four or more field tests. Selection indices were developed to use symptoms of rust infection observed in the greenhouse to predict parental breeding values for field resistance to fusiform rust. Of the 100 families, 75 represented an unimproved population, while 25 represented a population improved for rust resistance. A large number (56,688) of indirect selection indices were considered in an attempt to identify efficient indices which use a small number of traits. Indices were developed using three different sets of variance and covariance estimates: (1) from the unimproved population, (2) from the improved population, and (3) from the combined population. Separate indices were necessary for the two distinct populations. The new indices were more correlated with field resistance and result in more efficient indirect selection for field resistance than the equation currently in use by the RSC. However, the greenhouse test to indirectly assess field rust resistance (using the new indices) is somewhat less efficient than a single field progeny test on average. For. Sci. 38(1):45-60.

Relation of Nantucket Pine Tip Moth Attack and Fusiform Rust Infection in Loblolly Pine Families

Abstract The relationship between pine tip moth attack and fusiform rust infection was studied in a 12-year-old loblolly pine stand in Houston County, GA. Four pine families were selected for study, and 24 trees of each family were felled for evaluation. The lower 8 ft of each tree was cut into two 4-ft sections and split to reveal the pith. Each section was examined for evidence of pine tip moth attack and the presence of fusiform rust galls. The analysis revealed 476 tip moth attacks and 99 fusiform rust galls. Forty-six of the rust galls occurred at the same place as a tip moth attack. These results, when combined with those of previous studies, suggest that the control of the pine tip moth may reduce the incidence of fusiform rust. Growth and yield simulations and economic analyses indicate that insecticide treatment of loblolly pine for the combined control of the pine tip moth and the associated reduction in levels of fusiform rust infection may be potentially cost effective in stands managed for sawtimber, but not for pulpwood. South. J. Appl. For. 15(4):204-208.

Genetic Parameter Estimates for Greenhouse Traits of Slash Pine Artificially Inoculated with Fusiform Rust Fungus

Abstract Six-week-old greenhouse-grown seedlings of 100 open-pollinated slash pine families were artificially inoculated with fusiform rest fungus in three testing periods at the USDA Forest Service Resistance Screening Center. SIX months after inoculation, seedlings were scored for symptoms of rest infection. Genetic parameters (heritabilities, genetic correlations and family x test interactions) were estimated for 16 traits. Eleven traits appear highly promising for inclusion into a selection index to predict breeding values for rest resistance in the field. For these 11 traits, family x test interaction was not important, family heritabilities were high (>0.78), and differences among the four groups of families were minor for family variance, variance of family means, and heritability estimates. The other five traits had measurable amounts of family x test interaction and lower heritability estimates (<0.70). For. Sci. 37(3):836-848.

Symptom expression among half-sib slash pine progenies after inoculation with Cronartiumquercuum f.sp. fusiforme

Half-sib progeny from 106 slash pine (Pinuselliottii Engelm. var. elliottii) trees in a rust-resistant orchard were inoculated with fusiform rust (Cronartiumquercuum (Berk.) Miyabe ex Shirai f.sp. fusiforme) using the concentrated basidiospore spray system. Mass susceptible seedlings served as the control in each of the five inoculations needed to screen the 106 families. Relative susceptibility compared with the control was determined by the percentage of seedlings with galls 6 or 9 months after inoculation. According to the 0.70 disease ratio computation (percentage with galls in the test family ÷ percentage with galls in the susceptible control ≤ 0.70), 59 of the 106 families were resistant. The 0.70 disease ratio was more conservative at designating families as resistant than Fisher's least significant difference test (67 of 106 resistant), but was more liberal than Tukey's honestly significantly different test (42 of 106 resistant). Other symptoms of infection were recorded to determine frequency of occurrence. Multiple symptoms occurred on many seedlings; however, the symptom indicating the greatest susceptibility was used in the analysis. Galls, stem symptoms without any swelling, needle spots, and no symptoms were taken to indicate progressively decreasing susceptibility to fusiform rust. The largest variation among resistant families occurred in the frequency of symptomless seedlings (0–77% frequency among families in the five inoculations). The results from this study indicate that the frequencies of different symptom types observed following inoculation might be utilized to separate various types of resistance within a group of pine families characterized as resistant.

Fusiform Rust Incidence in Loblolly and Slash Pine Plantations in East Texas

Abstract A method to predict the incidence of fusiform rust (Cronartium quercuum [Berk.] Miyabe ex Shirai f. sp. fusiforme) in unthinned loblolly (Pinus taeda L.) and slash pine (Pinus elliotti Englem.) plantations located on non-old-fields in East Texas is presented. In addition, procedures are described to estimate changes in rust incidence over time as: 1. A rust-free tree remains rust free, develops stem or branch galls, or dies. 2. A tree with branch galls remains with branch galls only, develops stem galls, or dies. 3. A tree with stem galls remains with stem galls, or dies. Multinomial logistic regression models utilizing basic plantation parameters as predictors were fit to estimate current rust incidence and, then, the change in rust condition over time. South. J. Appl. For. 15(2):79-84.

Cytokinin activity in southern pines inoculated withCronartium quercuumf.sp.fusiforme

Cytokinin activity in tissue extracts from southern pine seedlings susceptible, moderately resistant, and resistant to the fusiform rust fungus was determined six months after inoculation. Qualitative and quantitative differences in cytokinin activity were detected among all rust-reaction groups and between inoculated and uninoculated trees within each pine species. Cytokinin activity in slash pines was detected at relatively low levels in 2 of 10 Rf zones bioassayed. After inoculation, cytokinin activity increased significantly within these zones, as well as in additional zones where activity had not appeared before inoculation with the rust fungus. Extracts from uninoculated resistant tissues were positive for cytokinin activity in all 10 Rf zones, whereas in extracts from inoculated tissues, activity was not detected in 3 zones and was diminished in the remaining 7 zones. Fresh weights of cocklebur cotyledons incubated in extracts from inoculated susceptible and moderately resistant seedlings were sign...

Monoterpene Composition and Fusiform Rust Resistance in Slash Pine

Abstract Cortical monoterpene composition was determined for 43 relatively resistant and 42 relatively susceptible slash pine clones selected on the basis of their fusiform rust resistance breeding values. Fifty-seven percent of the clones having high proportions of β-phellandrene were relatively resistant, while only 15% of the low β-phellandrene clones were relatively resistant. Reasons for the relationship are not clear, but presence of the high β-phellandrene gene may be linked with other traits more directly involved with resistance. Certain combinations of monoterpenes, including particular minor constituents, may be more indicative of resistance than β-phellandrene alone, but further work is needed. For the present, tree improvement workers should consider determining monoterpene composition of candidate trees prior to progeny testing, and culling trees with low β-phellandrene content. For. Sci. 36(2):470-475.

Effect of ‘elicitors’ on extracellular peroxidase activity in suspension-cultured slash pine (Pinus elliottii Engelm.)

Peroxidase activity in the growth medium of suspension-cultured slash pine was observed over time and eliciting chitosan concentrations from non-damaging to lethal were followed. First significant differences in peroxidase activity were observed within 12h exposure to chitosan. Extracellular peroxidase activity decreased as chitosan increased until considerable cell death occurred and medium peroxidase activity increased. Chitin and fusiform rust mycelium elicited decreased peroxidase activity with no significant difference in viability. The highest levels of elicited lignification corresponded to the lowest extracellular peroxidase activity. Controls and the greatest chitosan concentration (which elicited 100% cell death) showed the highest peroxidase activity and no lignification.

Growth and Fusiform Rust Responses of Piedmont Loblolly Pine After Several Site Preparation and Regeneration Methods

Abstract Cutover pine-hardwood sites in the Piedmont of central Georgia were prepared by prescribed burning or drum chopping and regenerated to loblolly pine (Pinus taeda L.) by planting or direct-seeding. Site preparation had little effect on soil physical properties. After an average of 12 years, trees were larger in dbh and total height, the merchantable stand was greater, and distribution was more uniform on planted than on seeded areas. Regeneration from direct-seeding was enhanced more by intensive site preparation than was regeneration from planting. Neither fusiform rust incidence nor rust associated mortality was affected consistently by the intensity of site preparation, but both rust incidence and rust associated mortality were generally higher in the direct-seeded than in the planted plots. South. J. Appl. For. 14(1):18-24.

Association Between Fusiform Rust Incidence and CRIFF Soil Classification for Slash Pine Plantations in the Coastal Plain of Florida and Georgia

Abstract The association between fusiform rust incidence in young slash pine plantations and the CRIFF (Cooperative Research in Forest Fertilization) soil classification system in the Coastal Plain of Florida and Georgia was examined in two independent data sets: (1) 958 predominantly 5-year-old plantations from an industrial forest inventory and (2) 73 9-to-13-year-old plantations in a CRIFF research study. Rust incidence was calculated as the percentage of living trees with a branch or stem gall. Soils were classified into six groups (A-F) according to soil drainage and the nature of and depth to the B horizon. A third data set relates oak (alternate host) abundance to soil groups in 53 plantations. Overall, the very poorly to moderately well-drained CRIFF C and D group soils (flatwoods Spodosols) exhibit the lowest rust incidence (ẋ = 5.9% and 5.3%); the moderately well- to well-drained E and F group soils (Inceptisols and Ultisols) have the highest rust incidence (ẋ = 45.2% and 28.5%); and the poorly to somewhat poorly drained A and B soils (Ultisols, Entisols, and Inceptisols) are intermediate in rust incidence (ẋ = 18.4% and 16.5%). Oak abundance varied significantly within and among soil groups. In general, oaks were more abundant on E and F soils than on B and C group soils. CRIFF soil groups are useful to characterize regional rust incidence, but are not associated with rust incidence in individual plantations. Plantations of like soil groups exhibit high or low rust incidence depending on the mean rust incidence of the area in which they occur. South. J. Appl. For. 14(1):39-43.

Incidence and Histology of Stem-Girdling Galls Caused by Fusiform Rust

(...) Stem-girdling galls with a bulbous swelling above a constriction on the stem were found to disorganize the tissues of rust-infected trees much more severely than typical galls tapered at both ends. Infected seedlings with stem-girdling galls grown in a greenhouse died within 1 yr; those grown in the field died after several years. Statistical differences within families and single-gall rust isolates were significant in some greenhouse experiments. Family differences were also significant for stem-girdling galls in some field plantings but not others; this inconsistent relationship was undoubtedly due to significant variation among replications

Phosphorus fertilizer, soils, and site preparation influence loblolly pine productivity

Growth and yield of 12-year-old loblolly pine (Pinus taeda L.) plantations were compared among five subsoil textures, seven site preparation methods, with and without phosphorus fertilizer. Phosphorus broadcast before planting increased the mean size of the loblolly pine trees. However, soil differences significantly influenced stand survival, and the method of site preparation significantly affected total stand yield. Therefore, the influence of phosphorus on total stand yield depended on soil type and site preparation method. The site preparation-fertilizer combinations yielding the most volume per soil type were: on the Lucy, Ruston, and Wagram soils, shear-windrow site preparation with phosphorus; on the Kirvin and Shubuta soils, chop-burn-harrow site preparation without phosphorus; on the Calloway and Henry soils, double chopping without phosphorus; on the Sawyer soil, chopburn-harrow site preparation with phosphorus; and on the Boswell, Cadeville, Gore, and Susquehanna soils, shear-windrow-harrow site preparation without phosphorus. Soil differences and phosphorus fertilization influenced the incidence of fusiform rust in 12-year-old stands of loblolly pine.

Evaluating Fusiform Rust Symptoms on Greenhouse-Grown Slash Pine Seedlings to Predict Field Resistance

Twenty-two fusiform rust traits (symptoms) were evaluated in greenhouse tests on slash pine seedlings for their usefulness in predicting rust resistance in the field. Seeds from five to 20 open-pollinated parents of known field rust resistance were mixed to obtain resistant, intermediate, and susceptible seed lots for inoculation. Seedlings from these seed lots were screened in 12 greenhouse tests (4 wk in each of three seasons). Logistic transformation of binomial traits was used to reduce seed lot × week and seed lot × season interactions (...)

Annual variation in fusiform rust infection of slash and loblolly pine seed lots in time-replicated plantings

Trees from two putatively fusiform rust resistant and two susceptible seed lots of slash pine (Pinuselliottii Engelm. var. elliottii) and loblolly pine (P. taeda L.) were planted in 4 or 5 consecutive years at three locations in south Mississippi and examined annually for rust galls that originated the previous year. Disease incidence was usually less than 20% in the first growing season. Resistant and susceptible slash pine had light incidence of rust after about age 5. The susceptible lobloly pine often developed considerable numbers of branch galls after the fifth season, but most were several metres from the main stem of the trees. The resistant loblolly pine of Livingston Parish, Louisiana, never developed more than 23% infection in any 1 year in thirty 80-tree plots. The three remaining seed lots often exceeded 50% infection in some years, but differences among seed lots were usually small. Rankings of the four species seed lots or the six families that made up the resistant slash seed lot varied by trial (year planted and year infected). Replicating experiments in time on high-hazard sites for rust should better define occurrence and importance of location × family interactions.