Unit 12: Integrated Biological Plant Disease Management - Practice Quiz

1 What is a biopesticide?

2 Which fungus is commonly used as a biocontrol agent against soil-borne plant pathogens?

3 Which bacterium is widely used as a microbial biopesticide for plant disease management?

4 In biological disease management, what does competition between a biocontrol agent and a pathogen involve?

5 What is antibiosis in biological plant disease management?

6 Why are biopesticides often included in integrated plant disease management?

7 Which application method directly coats seeds with a microbial biopesticide before planting?

8 What is a biofertilizer?

9 Which microorganism forms nitrogen-fixing nodules on the roots of legumes?

10 What is a major function of phosphate-solubilizing biofertilizers?

11 How can biofertilizers indirectly help plants resist diseases?

12 Which beneficial association helps plants absorb phosphorus and water through fungal hyphae?

13 Where are many plant growth-promoting rhizobacteria naturally active?

14 Which is an appropriate way to use a biofertilizer in an integrated disease management program?

15 What is a botanical pesticide?

16 Which plant is a common source of botanical pesticide products?

17 Which active compound is commonly associated with neem-based pesticides?

18 Which plant material is commonly prepared as an extract for its antimicrobial properties?

19 What is one common environmental advantage of many botanical pesticides?

20 Why should the recommended concentration be followed when applying a botanical pesticide?

21 A tomato grower repeatedly observes damping-off caused by Pythium in nursery trays. Which integrated treatment is most appropriate for reducing the disease biologically?

22 A biopesticide based on Pseudomonas fluorescens is applied to crop roots. Which result would best indicate successful biological disease management?

23 A farmer plans to combine a living fungal biopesticide with a chemical fungicide. What should be checked first?

24 A foliar bacterial biopesticide gives inconsistent control of a leaf disease during hot, dry weather. Which adjustment is most likely to improve its performance?

25 In a field with a history of seedling root rot, when should a microbial seed-treatment biopesticide ideally be applied?

26 Two strains of Trichoderma inhibit a soilborne pathogen equally well in laboratory culture, but only one controls disease in the field. Which trait most likely explains its field success?

27 A biocontrol bacterium suppresses a fungal pathogen by removing iron from the rhizosphere. Which bacterial product is primarily responsible?

28 A phosphorus-deficient crop also suffers from a root pathogen. Which biofertilizer is most useful for improving phosphorus uptake while supporting root health?

29 A legume field is inoculated with an effective Rhizobium strain. How can this practice indirectly reduce plant disease risk?

30 A farmer applies a biofertilizer containing living plant-growth-promoting bacteria to saline soil. Which factor is most important for selecting an effective strain?

31 A biofertilizer treatment increases root biomass but does not reduce disease severity in a heavily infested field. What is the best integrated response?

32 Why should excessive nitrogen fertilizer be avoided when integrating nitrogen-fixing biofertilizers into disease management?

33 Which observation best distinguishes disease suppression by induced systemic resistance from direct pathogen killing by a biofertilizer organism?

34 A biofertilizer containing phosphate-solubilizing bacteria is applied to alkaline soil. Which outcome would most directly show that it is functioning?

35 A neem-based botanical pesticide is included in a disease-management program. Which application strategy is generally most appropriate?

36 A garlic extract controls a fungal disease in laboratory tests but performs poorly after field application. Which factor is the most likely explanation?

37 Before spraying a concentrated essential-oil formulation on a new crop variety, what should a grower do first?

38 A botanical fungicide has good activity but is easily washed off by rain. Which management decision would most improve disease control?

39 A farmer wants to combine a botanical pesticide with a microbial biopesticide. Which procedure best supports compatibility?

40 A plant extract reduces pathogen spore germination but provides protection for only three days. In an integrated program, how should it be used?

41 A greenhouse crop is repeatedly damaged by damping-off caused by Pythium aphanidermatum. A Trichoderma product suppresses the pathogen mainly through rhizosphere colonization and competition. Which application strategy is most likely to provide reliable control?

42 A grower wants to integrate a viable Bacillus subtilis biopesticide with a copper bactericide. Laboratory testing shows that the label-rate copper treatment reduces viable Bacillus propagules by 99% after direct mixing. What is the best integration decision?

43 In a factorial field trial, a microbial antagonist reduces disease severity from 60% to 40%, sanitation alone reduces it from 60% to 35%, and the combination reduces it to 10%. Under an additive percentage-point model, what does the combined result indicate?

44 A nonpathogenic rhizobacterium applied to roots reduces a foliar disease, but the bacterium cannot be recovered from leaves. Which experiment most directly tests whether induced systemic resistance, rather than direct antibiosis on leaves, explains the effect?

45 A foliar microbial biopesticide has a short residual period and performs best when applied before infection. Forecasting predicts two infection events seven days apart, while field data show effective antagonist populations persist for four days. Which schedule is most defensible?

46 A bacteriophage preparation controls bacterial spot in one field but fails in another where symptoms appear identical. Which diagnostic result would most strongly explain the failure?

47 After repeated use of a single microbial biopesticide, pathogen suppression declines even though viable antagonist populations remain high. Pathogen isolates now tolerate the antagonist's principal antibiotic metabolite. Which response best supports durable integrated management?

48 A siderophore-producing Pseudomonas biofertilizer suppresses a soilborne pathogen in iron-poor soil but loses efficacy after repeated iron-rich irrigation. Which mechanism best explains the change?

49 A crop inoculated with arbuscular mycorrhizal fungi shows improved phosphorus uptake and reduced root disease under moderate phosphorus supply. At very high soluble phosphorus, both root colonization and disease suppression decline. What is the best interpretation?

50 A nitrogen-fixing biofertilizer increases canopy density in a crop susceptible to a humidity-favored foliar disease. Yield rises initially, but epidemics become more severe. Which adjustment best preserves integrated disease management?

51 Researchers must determine whether disease suppression by a phosphate-solubilizing bacterium results from improved phosphorus nutrition or induced resistance. Which experimental design provides the strongest discrimination?

52 A compost-based biofertilizer suppresses Rhizoctonia in one batch but increases disease in another. The second batch has a high carbon-to-nitrogen ratio, unstable temperature, and low microbial maturity. What is the most appropriate management conclusion?

53 A legume seed treatment contains an effective Rhizobium strain and a second bacterium intended to suppress root rot. Plants show reduced nodulation only when both organisms are applied together. What should be evaluated first?

54 A multispecies biofertilizer suppresses wilt in controlled soil but performs inconsistently across farms. Sequencing shows that different strains establish under acidic, neutral, and alkaline conditions. Which redesign is most likely to improve robustness?

55 A biofertilizer improves plant biomass and lowers the percentage of diseased leaves, but the number of lesions per plant remains unchanged. Which additional metric is most important before claiming true disease suppression?

56 A neem-based botanical pesticide controls a foliar pathogen in shaded trials but degrades rapidly under intense sunlight. Disease forecasting predicts overnight infection following evening leaf wetness. Which application timing is most rational?

57 An essential-oil botanical strongly inhibits a fungal pathogen in vitro, but the effective concentration causes leaf necrosis in greenhouse tests. Which formulation strategy best addresses this limitation?

58 A plant extract contains several antifungal compounds, but chemical profiling shows that one compound provides nearly all activity at the field dose. Which resistance-management conclusion is best supported?

59 A botanical extract gives 95% inhibition of mycelial growth on agar but only 20% disease reduction in the field. Which explanation most directly accounts for this discrepancy?

60 A botanical contact fungicide is planned for use with a foliar yeast antagonist. A laboratory assay shows that fresh botanical residues sharply reduce yeast viability for 48 hours but not after 96 hours. What is the best field strategy?