Across Nova Scotia, we are shy on rainfall, with many regions entering into drought-like conditions.

As 0ur climate changes, longer periods between rain events is going to become part of the norm.  Dustin MacLean, Perennia Horticulturist and Plant Pathologist, has some insight to share on What Diseases to Expect in a Drought Year.

In some cases, drought conditions directly impact disease by making the environment more favorable for pathogen infection, disease development and disease spread on a number of crops. In other cases, drought may not directly impact the rate of infection, however, the impact of the disease may be greater due to the plant being weakened from the effects of water stress.

Damage from many of the diseases causing yield loss in dry years is not visible initially, only appearing mid-way through the growing season or later, in some instances. Most importantly, damage from diseases in dry years is often mistaken for water stress. Before applying fungicides for what is believed to be disease in the field and potentially using up what could be a very important fungicide application with a chemical that may have a very limited number of applications, you may consult with one of our crop specialists or send a suspected disease sample to the Plant Health Lab at: Plant Health Lab – Perennia.

Below, we have provided some information on what diseases to look for during a drought or dry year:

Root rots: Some true fungal pathogens (such as Fusarium and Rhizoctonia) do not need much water to cause root rots, and when they do occur in dry years, their impact on yield is often more severe because the crop is already water stressed. While some damage is evident shortly after emergence, much of the damage is not noticeable until mid-way through the growing season. Alternatively, fungus-like root rot pathogens (such as Phytophthora and Pythium) need lots of soil moisture to cause infection and are usually much less severe in dry years. The exception to this rule are diseases that need sufficient moisture for only a very short period of time, such as downy mildew, which only needs wet soils after planting to cause systemic infection that may result in plant death regardless of environmental conditions.

Stem diseases and wilts: Stem diseases caused by soil-borne pathogens (such as Fusarium and Rhizoctonia) may be unaffected by drought and are likely to cause high levels of damage and wilting to water-stressed plants. Typically, the greatest damage isn’t seen until later in the season, and again, may be mistaken for water stress and premature senescence. However, a number of the most common and devastating stem and wilt diseases (Verticillium and Sclerotinia) are heavily dependent on ample moisture for infection to spread.

Fungal Leaf diseases: The most dramatic shift in diseases that occur in wet and dry years is with regards to leaf diseases. Pathogens causing rusts and powdery mildews need only brief periods of free moisture (such as dew) to infect plants, and are dispersed by wind, without the need for water. Although these diseases may not be more common in drought years per se, the damage they cause to crops experiencing water stress are significantly worse. These diseases have the ability to desiccate a water-stressed plant very rapidly. However, leaf spotting and diseases that require rainfall for infection and spread are far less common in dry years.

Head/flower/fruit diseases: The vast majority of these diseases need water for dissemination and are far less severe in droughts (Monilinia, Anthracnose, Apple Scab, Fusarium Head Blight, Sclerotinia Head Rot, Stemphylium Blight).

Bacterial diseases: Most bacterial diseases are heavily dependent on plant wounding and water splashing for infection and spread, so we would generally expect bacterial diseases to be less prevalent during dry years. While this is generally true, severe thunderstorms can still occur in a dry year, thus allowing bacterial pathogens to infect crop tissue. An example would be Fire Blight of Apple, where trauma blight events may cause rapid infection of trees when major weather events (such as hailstorms or thunderstorms with high winds) cause injury to the plant tissue.

Nematodes: Dry soils may provide a favourable environment for nematodes, as plant parasitic nematodes gravitate towards root tissue while any predatory organisms retreat deeper into the soil in search of water, as well as the plant being weakened, allowing for infection to more easily occur. Additionally, damage caused by nematodes in drought years is often more severe than when water is abundant. Nematodes may also exacerbate the impact from other root and stem diseases by weakening the plant and providing wound openings for other pathogenic organisms to invade. Like many of the root and stem diseases mentioned previously, damage caused by nematodes is often mistaken for water stress and premature senescence and may require the discerning eye of a specialist to properly identify.


The Nova Scotia Department of Agriculture Environmental Stewardship and Climate Change Program is currently open, and has  funding to improve water supply.  The first deadline is 15 June, 2023.  The second deadline is in September for work this fall.  The beneficial management practices supported are:

  • BMP 124/125: Wells, dams, spring developments and reservoirs or tie-ins to a multi-use water supply pipeline as part of climate adaptation (pumps, power supply, monitoring devices, pump tests. Hook-up installation and consultant costs, materials and contracted labour costs for spring development – collection well, cutoff trench, or cutoff walls)
  • BMP 139: Water saving systems and management through cisterns, water use meters, and water level equipment. Including watering sanitation and cleanout systems

There is also the Resilient Agricultural Landscape Program (RALP), which recently opened and funds new ponds or the part that is expansion is 75% up to $30,000 assistance.  The application deadline for this intake is June 30, 2023.